<human>: Could you distill the essence of the text into 1-3 sentences?

So to cut a long story short, me [25 f] and my partner of 6 years [24 m] broke up. I spent the following weeks getting quite drunk and ended up having a one night stand with a buddy of mine [25 M], which was very briefly unprotected. A month later, I end up hanging out and then hooking up with my ex partner again, unprotected... This morning my buddy rang me and said he'd tested positive for Chlamydia. He can't have got it from me, as I had a pap smear a few months ago, and got tested for STI's at the same time and I had the all clear. I feel like a complete moron! There's still a lot of feelings there between me and my ex and it has always been very on off, we still love each other very much.

 I guess my question is how do I ring up my ex and break this seriously gross news without fucking it up forever? I'm going to get tested and find out for sure if I have it or not, but is there a way of dealing with this situation with some damage control because I am freaking out right now/wanting to take a week long shower until I feel clean again.
<bot>: How I tell my ex (that I still have feelings for) that I might have given him Chlamydia without ruining (the irony!) our relationship for good?