OP, I really feel for you and, in many, many ways, I'm very similar to you.
It's ok to feel angry about what you've been through. I am in a similar boat and have past experiences that only my DP knows about and, as a result, people around me struggle to understand my behaviour sometimes.
I have gained weight and lost it through a variety of methods. I've used foods to comfort and to punish myself. It's shit and you reach a point where it feels so overwhelming that you don't know how the hell you're going to start climbing the hill.
This will only work when you are ready for it to work. The way you talk about yourself and assume what people think about you is hearbreaking. You need to break the cycle of negative self talk by opening up to someone, be it your GP or another health professional.
Forget the weight loss, that will come with time. The first step is to start taking care of you. The more pressure you put on yourself, the more likely you are to trip up and beat yourself up about it.
On the food front, I've found reducing my sugar intake has helped massively with cravings and hunger. If I get hungry, I get anxious and will shovel whatever I can get into my mouth, so I plan and meal prep. If I know I've got something already made for dinner then I feel calmer and more in control. I say this as someone who has eaten a whole box of cereal in one sitting, so I know the struggle is real!
I eat low carb but not high fat. All my carbs come from veg. I buy bags of frozen broccoli and cauliflower and use that to bulk out my meals and add a protein like tuna or chicken. Again, what's clicked for me isn't even related to weight loss, it's about keeping my emotions in check because if I manage my emotions I can manage my eating much easier.
Yes, there are shit long days where I want a gin and a pizza or chocolate but I find they are fewer and far between. And if I do fall, I TRY not to mentally beat myself up as that results in me eating more as I think I'm a failure.
I'm waffling On, but you need to identify your triggers and then you can manage them better, plan for them, and leave them behind.
It's not easy, especially if you have psychological scars. I am on Sertraline and that has helped stabilise my mood massively (Not saying that will work for you as not a dr). I exercise with a PT twice a week and that keeps me good too, especially if I'm feeling low.
Be KIND to yourself. Don't ask your GP for help with your weight, ask for mental health support. I promise you then the hill won't seem as steep.