I can't pretend to solve your problems, but I understand how badly you must be feeling right now.

You're not a horrible person though. A good exercise someone recommended to me is to list the pros and cons (honestly) of feeling like a "horrible person", as opposed to a "person with horrible problems". I think you'll find that you're the later. Honestly speaking, I'd seek the help of a therapist. Without presuming too much, perhaps you have some deep-seated fear of rejection or low self esteem that leaves you feel victimised or lacking appreciation.

I know exactly what you mean about having a "devil inside you". There are definitely dark parts of us that we can struggle to accept. I think that, in the end, it's best not to reject those parts of you though. They might not be nice, but everyone has them, and bringing them to light and accepting them allows you peace of mind, and the ability to challenge them.

I really feel for your situation. Understand that it's never entirely your fault. It might not be what you want to hear now sweetheart, but everyone learns lessons in life, sometimes hard ones. As Rocky said, it's not about how hard you can hit, but how hard you can GET hit, and keep moving forwards. The fact you've made such loving relationships before will mean you can do the same in the future.

And hey, the fact you're posting here means you're willing to take the first steps. I believe in you! You are a good, sweet person at heart I'm sure.