I am so so so sorry this has brought you down. What's worse, of course, is that it was all so easily avoidable, this pain. If only you had just been able to reach out to someone, anyone or gone somewhere, anywhere rather than give in to temptation and go digging for information on him.
You've had a relapse my dear Lilly and the guilt, shame, hurt, and sorrow are all par for the course.
You feel hurt because he has moved on. Why should you be, you've moved on haven't you? At least you had. Addicts must move on and replace their enablers or they may perish from their own consequences. When she has been used up she will move on, too and he will be forced to find another. Until he runs out of elligible women to fit the bill, this cycle will continue.
You are angry at your sister for not telling you? Should any of the recovering alcoholics or addicts at SR be angry for someone not bringing their DOC to their door? In fact, wouldn't that be the cause of great anger. Thank's buddy for bringing by just the thing I don't want to see again...ever! You are angry because she did not deliver your DOC on a platter and tell you all about him. That's just misplaced anger at yourself, I think. She was helping you, not hurting you.
All you can do is start again on your recovery. Start anew. Pull out some reading material or look up threads on letting go. I wish I could say something to make you feel better, but relapsing is supposed to suck so bad you don't want to do it again. Write how you feel down on paper, leave nothing out. Then, if you ever feel the urge to look him up again, you can remember how you feel right here and right now and maybe stop yourself before you go down this road again.
Written with care
Alice