How do I deal with my emotions post rocky on-and-off relationship?

I have a long and drawn out story with a back-and-forth ex of mine that has made me feel all kinds of ways; totally confused, disgusted, bitter and a kind of lingering anger I have never felt before. The feelings I’ve had towards him and how our relationships played out have just been eating at me for years. We met about five years ago and developed an on-and-off relationship that lasted a couple of years, even though our official period as a “couple” was only about 3 months. It may sound weird, but this is also why I’m so unsure of what to do with my emotions. The whole rollercoaster nature of him and I has messed me up. He was the one finally breaking up with me even though I wasn’t entirely sure or happy about how things were between us either. He has since moved back to be in a relationship with his ex-girlfriend that he dated before me. Or they may have started/continued things while he and I were seeing each other. I don’t know, because he wasn’t exactly truthful or open about any of his emotions whilst I needed him to be. I also want to preface by saying that yes, I know that by being involved with someone who can’t make up their mind about you, you are putting your own worth down and accepting shitty conditions, but I didn’t know any better at the time and nobody is perfect. So please accept that that is how I dealt with things and please don’t judge me too harshly for it. ☹ I want to focus on the now since that is what is driving me crazy. We share a group of friends in quite a small area of the town we both have lived in in the last 5 years, and it is very noticeable how relations have progressed since he got back with his ex. He seems to just live on, and has adopted the method of never explaining too much, all the while maintaining the exact relationships as before he and I got together. It is as if things never happened between us, he is the director of this narrative, and thereby everything just looks better when we are both in the same space at a party or some other social occasion. I do not agree with this narrative, and since we shared intimate emotions and super intense sexual chemistry (which I know for a fact is something he felt too) for years, it is just mind-boggling how he can get away with this and extremely condescending to me. Ever since I learned that he is back with his ex for (seemingly) the long haul going on two years now, the anger I have towards him has just intensified. Since our break-up was never really clear and abrupt, all the sense-making is something I am having to STILL do since he doesn’t offer any kind of clear explanation or even empathy. The worst part of this is that I find that he has succeeded. People, i.e our shared friends, still treat him as if he is this cool guy who throws parties and is “sweet” even though many know he has treated girls in quite shitty ways while dating them (including me! Not all our friends know, but I think they don’t want to know what he’s actually like in a relationship… easier to pretend like everything’s fine, right? For the benefit of the group). In the meantime, I have kind of been blurred out and disappeared into the ether. It is so infuriating I don’t even have enough words to describe what it feels like. Not only has he messed with my emotions for years, he is also making it nearly impossible for me to hang with our shared friends since I can’t stand his presence anymore. More so, I can’t stand to pretend to agree with the false narrative HE has created about us and that we are somehow fine now or even amicable. I am currently living in a city about half an hour away. One main reason is I am so not dealing well with how things are with our shared friends. It has really made me lose trust in both them and honestly in many other people as well. I know I have people who care for me, but most of them live in my hometown, and I just feel so lonely in having to deal with all of this. I have dated lots of people since him, even had shorter relationships with three different people, but after they have ended I always seem to get back to feeling such visceral anger towards him specifically. Just the thought of something he said or did years ago can make me start crying in a minute and make me spiral into this hole of bitter emotions where I just want to scream my truth about what happened. I really don’t know what to do with all these emotions, and I really don’t know what the best way is to move on. Like I said I have dated others, but it doesn’t remove the feelings of anger I have. I guess if it isn’t clear from what I just wrote, what has messed me up apart from the rollercoaster nature of our relationship, it’s that he acts like everything’s just fine and that I should just move on. This is something he always did in our relationship and still does – ghosting me and making me feel like what I am going through isn’t important. I guess I just need any tips or advice from anyone who has gone through something similar. Even though I hate him now, he was once very close to me, probably one of the closest people to me. It’s just painful how things have spiraled and it definitely has changed me and my feelings of trust to other people.