NEED ADVICE

So me & my bf have been dating for 9 months. He is Mexican & fluent at Spanish and I am Black/Panamanian & moderate at Spanish. The first few months were amazing , a few bumps in the road and then his mother got married and now he has a new stepbrother. After his stepbrother came. Our relationship has shifted. We went from being with eachother every single day to always arguing , him going to play soccer with his stepbrother all the time instead of usually going to go play with me, not picking up the phone when he’s around him, and smoking pot. Which he’d stopped doing when we first started dating. I also went through their text messages and his stepbrother called me a derogatory name. When I confronted my bf about it he said he handled it. At one of my bfs games, me my mother and aunt were talking to my bf and the stepbrother came up and cut my mother off rudely and she checked him about it. I’ve already had problems before with his sister and her husband but my bf actually put his foot down like a MAN & let them know I’m here and I’m who he’s going to be with. But what’s going on with this step brother bs? I was around before him and he barely knows him! Now he’s with him dam near every day & told me that he “needs space.” It’s been like this since the wedding last month. What is going on? My real theory is that he thinks he’s better than my bf because he dates within his race & he’s definitely said little racist sh*t that he dosent think I caught. What do you all think? & should I just fall back off my bf because if he continues to hang out with him over me then what am I really here for?