Sorry you are in this situation -- it stinks. You seem like a really good man, too good, in fact. I'd say you are nice guy. And you know what they say about nice guys?
Sorry to say this, but situation is about to get much worse, in fact you are about to go through the greatest sh*t-storm of you life. So listen closely.
1. Being the nice, needy, "best friend" while you wife is planning to leave you, gets a new apartment, has an OM in the picture, and then tells you she wants a divorce is clearly not working. The only thing that's going to make your wife think twice is your continued GAL activities, PLUS hard-core Last Resort Technique AND a strong stance about what YOU want should you move towards divorce. Right now the best person who can give you any advice is Starsky on these boards. Do EXACTLY what he says. Your wife doesn't respect you and isn't very attracted to you. I don't know if it's possible to re-attract her at this point. I think even MWD would recommend getting more hard-line at this point.
2. I don't fully understand the situation with your foster-children. How long have they lived with you? Do you BOTH want to adopt them? I'm about to say some very unpleasant things. Do you think this is the best time to be adopting children -- as you are about to potentially go through a divorce? The reason I say this, is that if you successfully adopt them, and the divorce case goes in her favor you may be financially liable for those kids, perhaps for the next 21 years and yet, perhaps, they are going to be partially raised if not mostly raised by another man. Sorry if I'm sounding crassly pragmatic. It may not be the best thing for these kids to be getting adopted into a sh*t-storm of a divorce with an OM involved.
3. You need to accept the fact that, given your wife's behavior, you are moving into an adversarial situation. She wants to keep the kids, she wants the house and she probably is going to want child-support. It's time to speak to a good family law/divorce attorney ASAP. Know you rights. I don't know what the laws in your state are, but collect evidence of her affair and start logging how much time you each spend with the children. In some states the person who has the kids more than 50% of the time get ALL the child support from the other person (as much as 35% of their income). In some states if it's 50/50 custody, the parent who makes MORE money pays ALL the child support to the other. In some states child support is calculated based on custody arrangement. DON'T tell your wife that you are collecting evidence, DON'T tell her you have consulted an attorney. Also, you wife leaving the marital home is not good for her case. You may not want to let her take the kids, which may hurt you later on. Talk to your attorney about what will protect your interests best. Maybe she gets to see the kids every other weekend, etc. or 40% of the time. Also talk to your divorce attorney about adopting the kids and what that means. Does she need you to adopt those kids? Does that give you leverage? Can you adopt them without her?
4. Prepare yourself for a divorce. Stop being a deer in the headlights hoping your nice guy routine is going to set the clock back and make everything better. All the evidence says your wife is about to run you over with a truck (financially and legally). So, if you are going to get divorced think hard: WHAT DO YOU WANT? Full custody of the children, possession of your marital home, 50/50 custody? FIGURE THIS OUT NOW. If you don't, your wife or the court will be deciding this for you. Do not drag your heels. The longer you do, the more contempt she'll feel towards you and the more vicious she'll get in the divorce. A friend of mine was being the nice guy in his divorce. His wife got the kids, moved out state with her lover who is raising my friend's children with her AND he has the privilege of paying child support to his ex wife and her lover.
5. You said the OM was #1 in her mind and you are #2. WRONG. She OM is #1, her kids are #2 and you aren't even in the picture. Sorry. If the best interests of your kids were in her mind, she wouldn't be getting a divorce. And if this drags on long enough, she'll try to destroy you. Your best shot at getting an equitable arrangement in the divorce with a functional relationship with you ex is to be clear and strong up front. This also may be your last shot at re-attracting her.
6. Why are you kids hanging around the OM and his kids? You can get a judge to stop that if you want. Most judges don't look favorably at a spouse introducing their kids to their lovers while still married. It's up to you dude. But it seems that you are OK (at least in your wife's mind) with all this behavior -- which is not attractive to your wife. You're not the invisible man. Show up. Take control of your life. Lay down some boundaries. What if she asks you to wait outside with the car running for her while she stops in for quickie with the OM, will you accept that too? Sorry for being so crass, here. I'm hoping you'll snap out of YOUR fog.
7. I refer all people to the Chump Lady webiste. It's hilarious, but like a whack on the side of the head to people who are trying to "nice" their cheating spouses back in to the marriage. It's a much needed tonic.
