Why is my anger coming out when drunk?

Recently I’ve just been spiraling massively. I think since January I’ve not had one night out with my friends where I’ve had a good time. I keep drinking and getting too drunk to the point I black out and can’t remember anything and then I’m told repeatedly that I’ve mistreated my friends, sworn at them, said rude things. Things I would never ever do sober and I’m sick of feeling the shame and guilt afterwards. I’ve spoken to my therapist about this and she told me it’s because I feel all these intense emotions like anger, jealousy, bitterness, anxiety and I judge myself for feeling them and then push the thoughts away so everything comes out when I’m drunk but I don’t understand how else to process these emotions and how to not push them away?

For some further context, the guy I was seeing in my group of friends is now flirting/extremely close to my bestfriend and it triggers a lot of anger, jealousy and bitterness from me. I try to accept it and move on, especially because I don’t even have feelings for this guy anymore and I don’t want him but I think my ego has taken a massive hit and it’s making me go crazy when we’re all in a group together. I over think and over analyse the way he is with her and look into every little thing and I feel so sick of this. Why do I care? Why do I care to the point that I’m lashing out and fighting with my closest friends? I’m also worried about what alcohol is doing to me and how much it affects me. I tell myself before every night out not to get too drunk and not lose control and some how it always happens and gets out of hand somehow.

Am I bad / cruel person? The things I say to my friends when I’m drunk disgust me and I can’t believe I’ve said them. Everyone online says that drunk words are sober thoughts and yes to some extent I do have resentment towards my friends for the situation but not to the extent of the hateful words I’m saying to them