Do I tell him I have an std?

So I’ve been dating this guy for a while and I really really like him. Like I can genuinely see a future with him. And we already slept together with a condom and it was great whatever. About a week after that my ex (last time I saw him was June) texted me saying he has chlamydia. And him and I wouldn’t use a condom bc I was on the pill at the time.

I’m going to get tested tomorrow morning because my ex also slept with someone else so I’m praying it wasn’t during our relationship (but we did take a break while we were together so I shouldn’t be surprised)

I’m worried and upset but I’m happy that it’s treatable.

Now as for the new guy I’m dating. I WILL tell him. I just don’t know when or how. Should I wait for my results and then tell him? Or should I tell him tomorrow? And how do I tell him without me sounding dirty and risk him leaving me over this? I really had no idea and I don’t even think I have chlamydia but I don’t want to take my chances and not get tested.

What do I do? How do I tell him? Like what do I say. I’m so nervous. Like how do I let him know that I’m not dirty and sleeping around??