I hate myself 😢

So lately I've just hated myself so much that I truly think it's starting to take a toll on me. Almost a year ago I found out my boyfriend was cheating on me. I broke up with him and about 3 months later we got back together. Some of you may say that's stupid but you can't help who you love. Well anyway every since this has happened I constantly put myself down. I truly just don't feel good enough. Since the start of my relationship I went from 165 to 185 and I feel disgusting. My boyfriend is always trying to fix what he's damaged and constantly tries to make me feel good about myself but it just doesn't help. Maybe it's bad but I find myself sometimes looking at the girl he cheated on me with Facebook and it just makes me realize why he would do what he did. Even though he's been good since we got back together I just can't get over it. No matter how hard I try. I just want to feel beautiful and not hate my body or my looks. I try so hard to be confident but I just can't. I'm not saying that the situation that occurred is the main reason I feel so ugly but it's a big part. I don't know what to do to get out of this funk. 😢 I'm not looking for pity just some serious advice.