How to break up with boyfriend civilly

1200 words is not enough for me.

Long story short, I need advice on how to break up civilly.

My boyfriend and I met on Bumble in August '19. While we were talking, I was also talking to a half black guy. I ended up letting the half black guy take advantage of me. My boyfriend does not believe in interracial relationships and had a hey day. Keep in mind this happened before my boyfriend and I became exclusive. We never officially decided to be exclusive and just went along with it. Well now, he's still holding onto it and using it to belittle, berate, and blatantly disrespect me even though I've been trying to effectively communicate verbally my boundaries and what I expect. Due to what happened, he believes I should be thanking him for staying with me and honored he that he still sleeps with me.. So, during this time, we bought a truck under my name, combined both our phones under my plan, and signed a year lease in a new house amongst other stuff to help my credit while he helps financially. He still uses the black guy, can't get over it, and is using it against me in all aspects. How do I approach him? His birthday is this Saturday, for goodness sake.

I'm not a gold digger. I'll be more that happy to sell back the things we purchased for us so that he can have it. Its some of these financial commitments that we can't just drop suddenly.