How long could I been mad at my mom for sleeping with one of my friends?

Anonymous
So basically my mom has very bad depression ptsd anxiety and ocd. She tends to use alcohol Xanax and weed to cope with this. My mom tends to get very aggressive and gets extremely emotional and likes to play victim in situations where she’s not (backstory my mom has a very violent childhood this is why she has most her conditions) my whole family knows and understand this. So December of 2021 my mom decides to call a few of my guy friends over to help fix her car while I’m at work and unaware. She tells them over and over I’m omw home (which is not true) when they finally realize this they start calling asking for me n asking where was n I was never omw home. they decided to leave when they realize this and they start to feel uncomfortable bc my mom offered the to come in n drink alcohol but of course one of them stays. When I come home from work I see them alone in my room together and they are drunk so i to leave when I come back the next day he is still there he tells me he slept with my mom and laughs then finally leaves (my mom by the way knew I was uncomfortable with him even being there but she said I was being disrespectful and it was her house and she can invite whoever she wanted to in) I confronted her she denies it then gets aggressive trying to hit me then admits to it and says oh well he’s 18 (his birthday is 5 days after mine we are freshly 18 and seniors in hs) she then Starts calling all my friends telling them i have stds, ima liar, everyone in my family hates me etc. I tell my family ofc n they don’t seem to really care and say I need to forgive her. It’s now 2022 June 6 months later and I can't seem to forgive her and my family says I need to but do I have to? My family’s says she has mental illness n I don’t so I have to be the bigger person but I just can’t especially when her behavior hasn’t changed so can i stay mad?
How long could I been mad at my mom for sleeping with one of my friends?
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