I wouldn't read too much into anything she says right now. Just because she didn't go out last night doesn't mean that she's not enjoying the single life. She's obviously enjoying it enough to separate from you - sorry, but that's the truth.
Again, focus on you and your son. Don't read into things she says - stop trying to figure her out and spend your time figuring YOU out. It was great to hear what a great time you had last night. Keep up the GAL'ing and PMA.