help needed 😭😩

Recently me & my SO were arguing & it was a really heated argument. I went out with my girls later that night to blow off some steam & to get my mind off of the arguement. To make a long story short, I had gotten drunk and ended up having sex with my ex 😩😭 2 weeks later I went to my check up & found out I have chlamydia! How can I tell my SO that I one cheated on him & two I had caught chlamydia (I'm cleared now & I didn't have sex with my SO until I found out that I was cleared)