Self-Sabotage and My Friendship. Vent?

I just wanna preface this and say that I never would intentionally hurt my friends or cause any harm to them whatsoever.

Around last month or so, my friend told me that I was ruining my friendships.

Maybe not like that, but that was the gist.

Apparently, I was unconsciously/not intentionally insulting my friends.

I, of course, never meant to. Though according to my friends, "It's pretty obvious you shouldn't insult your friends."

Which, now that I'm writing this, I sound stupid. Though I thought it was banter. 

Said friend also told me that it was so bad, to the point that one of my friends was thinking of leaving the friend group and if she left, everyone would go too.

You might be thinking, "Why didn't they tell you?"

Well, supposedly they tried, and I ignored it.

Which I do not recall, and if I did remember that, I would have stopped.

I cried after finding that out.

And ever since, I've had a fear they might leave me. I've been trying to be happy, and I was, for a while. Until something shifted. I don't remember when, but I felt uninvited. I've tried controlling my behaviour, but I find it incredibly hard because I snap sometimes.

Example: My friend took a piece of my croissant, and I said, "Who the freak* do you think you are?" (Obviously in an annoyed tone) I felt terrible right after, because she instantly apologised and gave it back. 

Keep in mind, I don't care if they take my food; I just get super surprised and snap at people when they take my food. This has happened twice, perhaps even more.

There are many more examples that I am not bothered to explain.

Anyway, continuing with the feeling uninvited. When I feel that way, I just want to leave and be alone. But previously, right after a breakup with a close friend (I had a crush on her yada yada), I couldn't stand being around her, because obviously I missed her, whatever. So I would walk away from them, leading to said ex/close friend to be concerned for me.

Quote from reality check friend, "She cares about you more than herself."

And my irrational self can't help but feel frustrated. (Btw, irrational me is not what I actually think.)

Irrational me: "If I'm such a bad friend, why don't you leave me, huh? Cause I'm such a bad guy. Why care about me? I hate that you care. It's not my fault she cares about me; it's hers.

I think I had more to say, but I don't really remember. All I know is that irrational me was mad that I was painted as a bad guy.

Which, now, I obviously did bad stuff without meaning to.

And I am most likely the bad guy.

Moral of the story, due to my fear of abandonment, I feel the need to leave the friend group because I don't want to bother them.