I know you're concerned with how your therapist might react, but I have a feeling she'll agree completely with the above. The guy deliberately withheld information from you for his own benefit. You never would have gotten involved had you known he was still married, which means you are NOT a homewrecker. (That term is usually reserved for those who stay involved with married people and don't care about the detrimental effects to that person's marriage/family. Which is still misplaced blame IMHO because the person doing the cheating is the one actually wrecking their own home. But I digress.) And if your therapist insists on labeling you that way nonetheless, that suggests she's already too biased and short-sighted to be of much help to you anyway.

I'm sorry you had to deal with that lying jerk.