How to be myself again?

Hello. I’m 20/F and have been in a 5 year relationship. Have you ever heard of “healthy relationship weight gain” well that is bullshit. When I first met my now husband 24/M, I was 132 pounds, 5’1 and in my “prime era” we started having relationships, I started taking plan bs… and eventually my periods went all crazy and I started gaining weight like crazy. I became depressed after gaining 30 pounds. And the depression just made it worse. I now weight around 220. Being more than 200 pounds and being my height, is not easy. I have terrible pains all over, I can’t breathe at night, I can’t even walk up the stairs without being out of breath. I absolutely hate myself and have tried everything to lose weight. I understand my 15 year old body won’t be the same as my adult woman body …but I just want to feel better and be better. I’m a useless, unemployed, person who doesn’t even go to school because I’m so embarrassed about how I look. My husband pays for everything and owns everything, I’m scared he’ll get tired of me being this way and leave. How can I be better??? How can I finally get motivation to do the right thing.?