Just... why

Been struggling with pp depression for almost 3 years (2 baby’s in 2 years) I’ve gained weight, loose skin, hormonal changes, acne break outs. But once I start feeling confident in myself, me and my SO will have sex, I’ll actually do my makeup, take pictures of myself to send to him at work (usually just take pics of what the kids are doing each day) and then I find him talking to another girl, watching webcam girls, commenting on other woman, and then I go back to wearing baggy sweaters, hair up, no makeup, and bad thoughts of myself to the point when I look in the mirror I cry. Idk what to do. Idk how to leave. I feel stuck and I’m scared to be alone. 💔