Hi Lisa,
I'm sorry to hear that you are in a hard place. But the good news is that you know what the problems are and are looking for ideas and help. It's a good start.
Lots of times depression, anxiety and a host of ills masquerades as weight gain. It is not the problem in my experience, it is a symptom of other problems. Many of the core problems (lack of self esteem, self destructive behaviors, relationship problems, etc.) need to be addressed alongside eating better and exercising for you to emerge a beautiful, fit, happy person.
Losing weight is a good place to start because you can do it yourself. Now I am not a Doctor, or a Psychologist or a fitness counsellor- but you should talk to one of each of these professionals before making any steps involving surgery.
I know how the thinking goes: "If I lost weight, I would have more self confidence and my Relationship would get better (or I'd have the strength to end it) and all my troubles will go away!
Trouble is that if you don't deal with the thought patterns that landed you where you are now, then losing weight is just rearranging the deck furniture on the Titanic.
Wishing you Peace and Success!
David