How to bring up the dreaded "are you clean?" Talk

So my fiancé and I have been sexually active for about six months. He was my first, but he has an extensive sexual past. I brought it up one time expressing my wondering feelings if I should get tested. And he seemed absolutely crushed that I would even consider that. Like he looked like he was about to cry and he couldn't look me in the eyes for a couple days. That was a few months ago and now I feel that for my peace of mind I want to be tested. But I feel like he would find out about it in some way or another. I don't want to go behind his back but if I tell him he will be crushed, but this is my health! I just don't want to have an sti and not know about it either because that could be very dangerous. Should I bring it up to him?