My wife has found a new girl friend who hates me; is this a prelude to divorce, what should I do?

I went through exactly the same. If you believe you are at not fault then the relationship is over. A therapist may help but the chance is a remote one, and not only that it is going to cost you money which is what most therapists are interested in. My advise is to talk to your wife and let her know how you feel about the whole thing. And if she shows you an attitude then divorce may not be to far in the horizon. Make your choices and protect yourself.