Start focusing on yourself. Set boundaries. Tell her you are going to the gym at this time no matter what. Grab beers with the boys. You need to put her in her place, thats what women need. A firm hand.
Here’s the difficult truth: She used you to be a baby daddy when she was pregnant with some other person’s kid. She never really loved you. There is a strong probability she has monkey branched/cheated already. It’s over dude. It sucks, but it will be better for you in the long run. Lawyer up, hit the gym, delete Facebook.