if he is still expressing interest, i think its only fair to be completely honest with him and give him the opportunity to decide whether or not he can handle your truth and still pursue something.

what would happen if things become serious between the two of you and you told him months, or years down the line? If he already has trust issues with women, that could just make it worse.

he may or may not be able to deal with what you tell him, but at least give him that choice to make the decision.

Or.. you could just break it off with him completely..

just my advice. best of luck!