My boyfriend (M34) is making me (F23) choose?!

Okay, so this is a long post so bear with me please.

I've been in a relationship with a guy for a few months now. My best friend, Brienne, who I met at college 5 years ago, wasn't thrilled when I first started dating this guy, because of our age difference and his job which, in her words, causes a power imbalance in our relationship. She also doesn't like people in this profession so one could say that she was a bit biased. She advised me against dating him and wasn't happy when we made it official but after I explained to her that I'm not breaking up with him, she respected that. Still wasn't happy but also understood it was ultimately my decision.

After some time, I thought about taking them both out so they can meet each other (big mistake). I was hoping that once Brienne met him, it would change how she sees him and how she sees our relationship. Not only did it NOT change but it made everything even worse. She said that he is not a good guy, that our relationship wasn't going to end well for me and other bad things about him. She didn't insist, she just said that she has to advise me as my best friend and be honest with me.

Moving forward, less than a week later, my boyfriend tells me that I have to stop talking to Brienne and cut her out of my life. It caught me off guard. Brienne is my best friend and although she doesn't like my boyfriend or our relationship, she respects my decision to stay with him and hasn't talked of him or our relationship again. I asked him why and he said that he thinks Brienne is a bad influence. He then said that he also doesn't like my other friend, Nikki, who by the way he has never even met as Nikki lives away. That confused me so much. He said that I have to stop talking to them or hanging out with them and told me to delete or block their numbers. I said that there's no way I'm doing that and then he said that it's either them or him. My jaw dropped. I tried to resonate with him but nothing. I haven't stopped crying. I don't know what to do. I love my friends more than anything but I also REALLY want to be with him and I'm developing serious feelings for him. He treats me very nicely and I feel really happy in this relationship. I'm at a loss.