I know how you feel. We all do. Just focus on the few small changes you can make. A few small changes add up to big changes, eventually. And I think you getting on here shows some motivation. Also, all the other advice already given to you was exactly what I would have said
Sometimes we all need just someone to listen to us. And we're here. I know how you feel about the person that yelled about the fat lady. I once had a teenage girl come through my line at work, and she asked when I was due to have my baby. And without missing a beat I told her "i'm not pregnant, just fat". It killed her, and I felt better for having humiliated her. Bah. I wasn't proud.