I'm sorry you're going through this. In my own weight loss I've had several partial regains (just coming back from one right now, in fact. I gained about 15lb.) Even such relatively small gains have felt horrible and traumatic, so I can't even imagine how hard it must be for you. Maybe some things I have learned can be helpful:
-Do not listen to the negative voice, guilt, regret or self-hatred. Try to find your love for yourself and your positive reasons for wanting to lose weight again. Sort of like this: 'It's ok to be fat; my size doesn't determine my worth. But I would like to be thinner because it felt wonderful and I want this again, so I'm going to do it.'
-Don't compare what is to what might have been. We are not perfect. We can learn from success, but even more from mistakes. You may take longer to reach your goal, but you learned and grew along the way.
This quote always helps me to put everything in perspective:
And of course the quote in my signature!
Have a lovely, successful day