BEC, Stop talking to your wife about the relationship! She says she's filed, then you know what you need to do. Do not share any info that you receive from your lawyer about what will happen. She will find that out when the negotiations begin.
Evidently she is wearing rose colored glasses if she thinks that things will remain the same, i.e., scheduling fun time for herself and ringing you up to do the babysitting. That's not how custody works. Schedules are usually set and you and she will need to adhere to them unless agreements can be met. You are not an after thought, nor the babysitter when she wants to go out.
About the money, she'll need to get a full time position. You will need to ask your lawyer about her comment that you could take care of the kids at night when she works. That may affect the child support. Also, your child support will be based on what is allowable for your state, not by what she wants.
As for the mud slinging, your family should not be brought into it, i.e., foreclosures, etc. That's not your problem. In fact, if the home she's living in is in foreclosure, she needs to worry about that. Now, about your brother, that may be an issue and if he's not suppose to be around children, then you will need to make sure that the children are not around him. I know you stated he was a registered sex offender, but still this is some cause for concern for the legal arena and possible custody arrangements.
As for the drive bys, you've got to cut that stuff out! I don't know how many times we've told you to leave things alone and yet, you continue to do them. I can't believe you drove by there twice and yes, it was very obvious. You've pushed and pushed and now she's filing for divorce, or so she says. Stop all discussions w/her except about the children's activities, when to visit and paying the bills. Leave everything else at the door because you are digging your hole deeper each and every time you speak to her.
This entire issue should be between you and your wife. Divorce is business and quite frankly, neither of you married your in-laws. Leave them out of the equation. As for the interactions between your wife and sister...well, they've gone down the tubes and I wouldn't be surprised if your sister asks her to move out if things continue the way they are.
Again, do not discuss any info you receive from your lawyer w/her. Don't try to tell her what life will be like. She will need to learn that on her own and whatever you do, don't agree to anything she puts in front of you w/o your lawyer reviewing it and that includes money, visitation, etc.
Live your life for YOU and your children. Leave your wife to wallow in her own mess.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.