Unfortunately these friends were never really friends. They never saw you as an individual because they saw you as one part of a couple, and that's extremely sad considering how close you were. Even if the break up was an adult, mutual decision made by the both of you, your friends shouldn't take sides because they should be there for the both of you in your time of need. Although if you cheated on your partner and it all ended horribly, don't expect them to be a nice to you as they are to your ex. You'll probably feel the wrath of their tough love and you'll have to learn to become amicable so that you that you don't split up the group.
