Need some parenting help.....

[Dink]

Went thru my stepsons phone today. Found out he's been to 3rd base with a couple girls.......he's 13, in 8th grade. On one hand I wanna give him a high 5!! On the other, I'm terrified!!! Mom and I talked today, but really don't know what to do.

School gve them a sex-ed class at the end of last year, so now they aren't scared of it or embarrassed to talk about what they wanna do with eachother. BUT, he still wont talk to me or his mom......

Not sure I wanna tell him I know, cause he'll start deleting everything from his phone.......

This is our first teen, so I'm stumped.......

I just don't want to be a step-grandparent at 34!!!!