have you considered going to a different tattoo place? i have four myself, each one done by a different artist in a different state. i think you really need to avoid this person, and the best way to do that is to go elsewhere for the ink. at the very least, you could go when hes not working. by seeing him you might be feeding the obsession. i dont have much expereince with this kind of thing, but i do know that when someones impacting me negatively, i stay clear of them.
as for your marraige, these things do happen. you did nothing inappropriate. applaud yourself for your strength and resolve! the mind is a very strange thing. who knows why we find ourselves drawn to certain people. i think its human to develop little crushes now and again, and you need to forgive yourself that. stay away from the arty tattoo guy and focus on the hubby. when youre around your husband (whom you truly seem to love) remind yourself of all the reasons you fell in love in the first place. you are so lucky to have love! dont let it go.
i believe your feelings for the other will fade in time. but the best advice i can give is keep your distance. dont feed your obsession, starve it until it withers and dies.