You’re not a monster. You’re simply someone with their own problems, just like everyone else. Please don’t kill yourself. To do so would be to end your life before it’s time, to waste your one and only opportunity to live, and to hurt the ones you love deeply. This place you are in now is not forever, though it may seem like it.
If you’re surrounded by assholes, get out. Go somewhere on your own. Escape from it. But don’t off yourself to do it. There are good people in the world and you can see it in your true friends, as you say.
I can’t say much since I don’t know your circumstances, but I doubt you’re a monster or a crazy person. Your girlfriend cares about you. But for your relationship to work, make sure you give back. Just tell her how thankful you are to have her there to help you out.
Whether she deserves “someone better” (to paraphrase your words) or not is irrelevant. She has chosen you. Show your appreciation and do what you can to provide for her like she does for you.
And please, seek counseling, professional help, anything. If you’re on meds, it sounds like you already are, but don’t give up on it please. Don’t just post here, because no one’s going to stop fapping to try to help you. To post here is to expect further loneliness. I don’t come to 4chan often, but I’m sure there are some boards and a very decent number of people who want to help you out.
Ultimately, we can only help ourselves though, so please try not to give up on yourself. I know it’s not an off and on switch, but if nothing else, all your true friends, girlfriend, and this one anon way out in the universe care about you.
Stay with it. Do you’re best. That’s all any of us can do, and I wish you the best of luck out there.