So short little story here.

I dated this guy for a few months, and things got pretty serious and we had sex all of the time without condoms. Well we broke up and saw each other one more time months after the break up and had sex. Turns out he was seeing 3-7 girls the whole time we were together and after, but I didn’t know this until i saw him months later. The only reason I found this out was because I went through his phone. Well some girl had texted him letting him know she was going to the doctor because she had symptoms of an STD. After reading her text message I left but never told him I saw that message. Well I decided I needed to go to the doctor and get check just in case and then I tested positive for an chlamydia. I have been treated and have know I was positive for a few weeks now. Well my doctor says i need to inform my partners about it. Question is do I tell this guy about it, or just let him figure it out on his own?