Consult your attorney closely about this.
**I will do that at the first opportunity
Be clear on what more evidence gets you: legal leverage? personal leverage? something else?
**I believe when I do let him know I know more that he is going to panic, again, and want to "fix things". I plan on doing counseling if we can absolutely afford it and he wants to, that's going to be a hard boundary, because I think he has himself believing its "not that bad" and "it'll be okay". In that counseling I'm going to give him one opportunity to bare it all and come clean, and that will tell me clearly once and for all where he is at. The more dirt I have, the more I can determine his transparency. I need this, for ME.
I'm no expert in scraping phones for evidence but there are several options to consider. Is it part of a family plan that you are owner or joint owner of? Then he cannot argue you don't have legal right to the phone (I'm not giving you legal advice here but this is what my attorney shared with me). If you cannot reverse engineer his password (his birthday? your anniversary?), consider hiding a camera where he takes a crap and record him unlocking it (they always flirt online in the bathroom). Consider whether its possible to download his message history via a shared icloud account (or similar android setup) if you have family sharing or whatever. You might also consider arranging a late night phone scan while he's sleeping if you can grab the phone but not unlock it. There are services that can do things with the SIM card. Other miscellaneous ideas: can you collude with a friend to steal it? Can you buy him a new one for x-mas and straight "disappear" his old one "Yeah, I traded it in". Any other rouse you can play on him to get it?
**I'm toying with ideas now, and have been trying different passwords. I've thought about hiding a camera in the bedroom, that's the only place he keeps it. He never has it on him when he is home, even if he is expecting a call. I think there's a possibility of maybe lewd comments, but actual affair behavior right now I'm not worried about. He's been very open about trying to make me feel safe this past year. What I want to see is 1. Have the come ons to other women stopped since the affair, showing at least some change in behavior and 2. Is an old time period I believed he had an affair great an affair, or are there any other hookups I don't know about? He even told me during our last issue that there are "some things he can't ever tell me because it would hurt me too much". I trusted him then, and let it go. Now that I know what he's capable of I want the truth. When I confront him to give me the whole truth, I want as much evidence as possible for MY peace of mind.
Look, there are many opinions out there about "invasion of privacy" in situations like these.
**I don't give a rat's behind about his privacy. I've been digging through his computer for days when he's not here, and will continue until I'm satisfied I have as much as I can find. His old desktop is still on his desk, I plan on digging into that as well.
Know your rights to record conversations based on whether you are in a one party or two party state. See background here: http://www.dmlp.org/legal-guide/recording-phone-calls-and-conversations
and look up your state here: http://www.dmlp.org/legal-guide/state-law-recording
You might attend some MC sessions he perceives as a trend toward reconciliation. You might demand full disclosure. You might record those conversations. You might get something out of that, you might not. When he stops short of what you already know, tell him you know he's full of $hit but not HOW you know or what you know. If he SWEARS he's telling you everything, present an opportunity to prove it via POLYGRAPH. If he refuses he's basically telling you he isn't telling the full truth. He might scream and yell at that point about you should TRUST him blah blah blah but don't hold space for that noise. Hold your ground, don't be gaslighted into capitulation.
**this is exactly what I want. I'm not even as much concerned about what I can get out of him financially as I am wanting to finally, after 13 years, put these doubts in my head to sleep. I want to know. I NEED to know, at least I need to be able to tell myself I exhausted everything I could possibly think of to find the answers.
I don't know if you've said anything about knowing who the person is he is/was screwing but getting that info is important and if they are married/involved with someone else establishing contact with the other side is important. It removes control of the narrative from the cheaters and gives you plausible access to info that you either a) actually get or b) bluff as having.
** Of his affair, I already have proof. I have their entire messenger conversation screenshot and recorded and locked in a secure folder on my phone accessible by only my fingerprint. I sent her a message while I was confronting him letting her know I had all that and would not hesitate to use it if she forced my hand. She sent a screenshot of that to him, so he also knows I contacted her. He also knows I have talked to her Father. (He actually contacted me)
ALL of that is a tool to crack their secrecy and obtain evidence. Even if you establish contact with his accomplice you show some power and if you communicate independently he can NEVER know what you actually discussed. She may tell you something or nothing, but you can use the direct contact to bluff. Since they are liars and tell each other lies ALL THE TIME to maintain their stupid relationships, they know they are at risk of being lied to at ANY point. If you contact her, she may report it, he will ask what she said, she may say she said nothing, the SECOND you say she said something else (perhaps not based on something she told you but something you learn from their texts, as an example, tell him SHE told you this) he will start thinking he may be getting played, trust between them might take a hit and you can start playing them off each other. Devious...sure. But do you want to win? Or do you want to get treated like a doormat? Watch some spy movies, they are great for ideas...
**I did think about contacting her and asking her for screenshots of their texts, since I've not accessed his phone to have that. I could threaten to send what I have to her husband, or even make it public on their lovely social group, but I don't plan on doing that unless he really wants to fight dirty
Regarding the urge to "explain" your boundaries, consider this: he isn't explaining $hit to you, why do you owe him an explanation? SILENCE is JUST FINE right here. You are still behaving with responsibility and reciprocity as the organizing principle of your relationship, but he isn't offering that to you. When you get an urge to be reciprocal in any way with him check yourself and remind yourself that while yes it is constructive in most relationships it is harmful to you here.
**the only reason I want to explain my boundaries, or at least the reason for them, is because he has been reaching out to me and being loving. He knows something is going on, but I think right now he just thinks I'm in a funk and so he needs to reach out. That's why I am trying to figure out is do I want to stop him from doing that? Emotionally I don't think I can handle that. Ut how much do I want to reveal, or just go ahead and reveal it all, or at least that I know more than he's telling me and give him a chance to go ahead and come clean.