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Break up with him, go of to college, and after a few you still want to tell his wife, write her a letter or give her a call. After a couple of months, you will have had plenty of time to start a new life in a very social setting. Who knows, by then you may not care anymore about this guy or his wife. On the other hand, if decide that you do, in fact, want to tell the wife, you will have had time to straighten yourself out emotionally, and you will have much easier time dealing with the fallout.
There is, however, one thing that you must do immediately: tell the husband that if he contact you again in any way, you will go straight to his wife. Make it clear that you mean business and that you will not tolerate him trying to convince you otherwise. For example, if even so much as leaves his number on you caller i.d. inform his wife.