i want suck ex boyfriend of my girl in front of her!

You sound like a cuck in the making. Cuckolding is wonderful! Be sure to shave all your pubic hair. You don't have to have a cock lock, I think that one should be able to refrain from masturbating without permission by their own willpower. But all else is cool. Get on tumblr and to some research - many wonderful cuckolding sites! Good luck and please keep us posted :-)