I'm going to block my bestfriend on all social media, and break up with my girlfriend
What will happen if you break up with your girlfriend?
If I don't do these things my bestfriend might not like me anymore and break up with me.
You should not do these things to your friend and girlfriend. It could mess up your relationships.
I don't care.
It is wrong to ghost your friends and partner. You should not have to pick between them it is unfair to you. If they can't respect you  you should be able to move on and find people who will.