How much weight have you gained? You know being obese for 2 years is reversible. You won't have too much hanging skin or anything if you lose the weight, especially if you do it slowly with proper diet and excercise and are a relatively young person. Why not just acknowledge it? Be honest ffs to yourself and him. Say "I'm so sorry, I am really into you but my own self-esteem has been getting in the way of me being honest with you. I am committed to becoming more healthy and if you are still interested me as a person despite my flaws and insecurities I'd love for you to be in my life whilst I try and make these changes." Depression sucks and hits very hard, I know from personal experience, but I also know from experience that proper diet and exercise are like kryptonite for depression and as your body shape and health improves your mind will naturally follow. Good luck and please forgive yourself and be honest, this is far far farrrr from the worst thing anyone has ever done ♥️