First thing you need to do is quit being mean when you are nervous. That is not going to serve you well in life. Why not try putting into practice being nice when nervous and see if that works better for you, and see if he asks you out.
When I talk to my crush I'm kinda mean b/c I get really nervous and I always regret what I say afterwards.. should I tell them how I feel?
Do what you can to stop it. Whether if you're mean or if you're nice, you'll be nervous anyway. Keep that in your mind. Try to smile at him and always be mannerful whenever you can. If you can help him out with something, just do it.
I understand this completely. My crush was so nice to me => I got suspicious and nervous (because it never happened before) so I ended up kinda putting my guard up. Sometimes I was snappy towards him as a joke!!, but even now we don't talk like we used to. It really drives people away.
Yeah, you should totally stop being mean to your crush. It will cause your crush to be scared of you, instead of your crush liking you back.