<human>: Condense the text into a few key points

I just need advice on how to put this all behind me, it's been a year now and I just feel really shitty.

We were as close as siblings and due to a lot of crap happening and me just being a general idiot without knowing (may sound stupid but I have autism) I ended up damaging a friendship.

when I say idiot I mean doing things like showing off things I bought without realizing how it made her feel knowing she and her fam. had almost no money, Asking things from him without a proper thank you only doing so when told.

though afterwards I did find out both of them did shit behind my back that was inexcusable, She was soliciting my GF for sex and told her I needn't know about it.

and he was complaining and bitching to my GF about me even though he said he'd have my back and still be my friend.

Now I'm not saying I was the best friend ever, I know that i've made a lot of mistakes.

But my question is how do I get closure and just stop letting them pop up into my mind? 

It's gotten me in tears a lot of time because I just can't process what happened or what else I did wrong.

I feel I should Get Angry (Loud stomping foulmouthed expletive spewing wrecking all your shit angry)
but I don't know if I'm allowed to.

any advice?
<bot>: I had a friendship end on bad terms and in bad blood, How do I get over this and give myself Closure?