No one is helping your situation....including you. Your FIL and SIL are certainly talking to her and the more they push, the more she'll pull away.
One thing you should do, if you haven't already, is to indicate that you understand that she feels that way, you will respect her feelings, and that you are letting her go and find herself. I wouldn't say, "and I'll wait for you". Continue to be involved with your kids, and less involved with her. And please quit having these giant conversations every time she looks down. I personally think the best thing for you two would be to separate for a bit.
You cannot be lonely if you like the person you're alone with. Dr. Wayne Dyer
