I'm going to block my best friend because she got jealous
Why did your best friend get jealous?
She got jealous because I am friends with her boyfriend
If you were not friends with her boyfriend before they started dating, it may seem disrespectful to her that you both are friends now. It would be helpful to talk with her about how she feels.
Who fucking cares? I tell you why, because I can.
You should respect how your friend feels and place your relationship with her first. You would want her to do the same for you if it were your boyfriend that she was trying to befriend.