cheated on - - with my best friend

my ex boyfriend and i had been together for 3 years... we were in love, madly in love... and then a year and a half in i found out he was cheating on me with a lot of girls... like an idiot i took him back.. we lived together and i just didn’t think i could handle leaving him.. i finally tried to break up with him for good this spring but then i found out he had slept with my best friend in my basement while i was sleeping upstairs.. probably happening multiple times i assume.. but i lived with both of them, stuck my neck out and did all i could. apparently all of my friends knew and didn’t tell me, then they all abandoned me too... they all are still friends. left me for dead and went on pretending like i never existed... it’s been four months since i found out... i thought i would feel better, but i don’t... the haunting memories of them and everything won’t leave.. i’m doing my very best but i’m just a damn wreck. some days i feel i won’t survive this but i know i’m a strong woman who’s not going to give up that easy. especially for a bunch of assholes lol so if you lovely ladies have any advice or kind words for a hurting sister i would really appreciate it❤️