Why on earth have you stayed with this person for so long ? You do deserve more...you don't need to lose the weight and THEN leave...where does that make sense ? This has not been a true loving relationship & doesn't appear to be what he wants at all. You should be loved & accepted for who you are. How many of us started out tiny and gained alot of weight over the years and still our spouses loved us both emotionally AND physically, you can not have a healthy realtionship any other way ! You must lose the weight because you want to for yourself. I feel so bad that you have put yourself through such a long unnecessary hardship with this person...you have invested so much in a very unhealthy relationship and gotten nothing back. It's ok to be by yourself..I know you may think you need him but you really don't. Take care of yourself first, if losing weight is an honest piority for YOU ( not him ! ) then start down that road..read everything..decide what diet eating plan is best for you & go for it. None of us are perfect and we've all had our problems along this bumpy road of losing weight..but just keep at it and you can do it. There is always help through this site as well as lots of other sites...I use this one, also Fatsecret, Atkins, MyfitnessPal....use whatever you can get your hands on for support, you'll find people do care and want to help.
In the end you have to do what you think is right for yourself...no one is judging you, we just want to let you know we care and want the best for you.