Relationship advice? 10pts!?

The biggest thing to remember: it's your life, not your friends. You don't need to tell them anything, especially if they seem to keep judging you like they are. Just take everything one day at a time. Learn to be close to David and see how much you like him - you don't want to ruin Richard's current relationship, only to discover that you like David more. That will ruin not only his relationship, but his trust in you and possibly your friendship.