I really don't like the group of friends my boyfriend is in. They are rude, they are mean and my boyfriend actually acts really weird and actually pretends to be less smart then he is when he is around them

That does sound irritating
Have you communicated that to him?

One of my friends had the same problem, her then bf would be super lovely around her and his family but as soon as he would hang out with his school friends he was rowdy, rude and stupid. I think sometimes it comes down to self-esteem and wanting to fit in, especially when you are surrounded by other guys you don't want to be seen as "less of a man" and all that dumb jazz. I think you should ask your boyfriend about it and maybe see if he even notices his change in behaviour. In the end, it is his choice to be friends with who he wants but let him know you don't want to hang out with him when he acts that way.