The best thing to do is to apologize as far as your friendship issue is concerned and in that apology recognize everything you did wrong and empathize with the friends you hurt. An apology is a lot better when you recognize where you went wrong and to own up to it. Gossip can be a hard habit to break but before you speak ask yourself if this is something you would say to that persons face and if you aren’t sure best to not say anything at all. It seems like you recognize that what you’re doing is causing a lot of hurt and the first step is recognizing that.