Dating toxic ex’s best friend

So I was in a relationship (or so I thought) with my ex from October 2020 through May 2021. He was very distant during our relationship and we literally never went on dates (he claimed it was because of covid and him trying to save up to buy his first house). We broke up after he cheated, ghosted me, and I just felt drained from pouring so much of my energy and emotions into someone who wasn’t even giving me the bare minimum.

He tried to get back together April 2022 and I honestly wanted closure so we started texting and linked up once (no hookups) but I quickly saw he was giving minimal effort again so I told him to kick rocks to which he responded “Well hook me up with one of your bad female friends then.”

So me feeling triggered and in the mood to be petty told him sure, but only if he hooks me up with one of his homeboys. To my surprise he actually sent me a pic /contact info to someone I found suitable, so shit I sent him an acquaintance’s number too. Anyway so I get to talking to the friend and we click instantly. We chatted on FaceTime everyday for a week before going on our first date.

And the first date was truly magical..it actually lasted 48 hours, I went to church with him next morning, met his mom, and me and him didn’t even sex despite having insannnnne chemistry because he respected that I was abstinent at the time.

Meanwhile my acquaintance who I connected my ex with texted me saying I should’ve told her he had a kid, and I thought she was joking because to my knowledge he didn’t. I ask his friend about it and his friend admits that my ex had a kid in October 2020–I put the pieces together and we made our relationship official the day after his BM gave birth but we were hooking up for months before then 🤢 Come to find out this man had SEVERAL women the entire time and I wasn’t even in the top 3 🤣

Anyway knowing all this I continued to see the best friend and now we’e in a relationship and have been for 7 months now. It’s been incredible - we are deeply in love and have even discussed marriage and starting a family together. But I still hate my ex.

I wanted to have an adult conversation with him so that we could be cordial and move past the awkwardness and tension but when my boyfriend reached out to him to do this he refused. Like he just doesn’t care that he hurt me so badly. He didn’t care about our “relationship” or me at all. And idk it’s just super humbling to try to be cordial with someone who treated me like such trash, knowing they’re not even sorry about it. I don’t want to make my bf choose between the two of us but he’s saying how he would want my ex to be the best man at our wedding and our children’s god father which makes me physically ill to even think about.

How should navigate this yall? I never meant to fall in love or get in a relationship with my ex’s best friend. Should I break it off with him? Or try to get along with my ex even though he’s unwilling to take ownership of what he did to me? If so how tf do I just get over it?