Forced to share a hotel room with my ex fiancé! Advice?

My ex and I broke up 5 months ago and we had a very bitter break up over something private, neither of us cheated though! We haven't dated anyone else since we broke up and he has made it very clear he wants us to be back together but I cant agree to that until I am sure things can and will change, He is very short fused and i'll admit that I would play on that when he would annoy me which I now see is stupid and childish! Our two friends are getting married next Friday and we booked the hotel months ago and I tried to get a room for myself last week but they said the hotel is completely booked out so I have no other choice but to share a room/bed with him, Its the hotel that the wedding is being held in and the others are a bit of a drive to them. We haven't properly spoken since we broke up except if we bump into each other on a night out, He tells me he loves me still & wants me back and I tell him he'd have to change his ways before that happens which leads to us fighting, again! I know that this is going to be so awkward between us and I still love him too and I know there will be tension between us and im a little afraid we'll end up having sex because I don't want that to happen until we agree to work and fix our problems etc. How am I going to handle this, It will be from the Friday night until the sunday morning. Any advice is welcome!

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