my 14 year old got caught having sex with a family friend that is younger than him what should I do

As Taz says, that's a tough one.

When I was 14, you might have dated a girl one year behind you in school but not two years, without a lot of bad peer pressure. The distance between 14 and 11 is huge. I expect that would be considered rape in most states, consenting or not. At 11 she's not old enough to consent. The police are surely going to take a dim view of it but I don't see how you can keep it from them without commiting a crime yourself. Recent federal laws  have proscribed the reporting of such things by anyone who is aware of it. Most states have backed that up with their own laws. Even priests at confessions are not immune to our current laws. Most police departments can lead you to supportive counseling but they are probably more interested in the legal aspects.

You should certainly be getting some professional counseling for both of them and all others involved, such as parents.

I don't think this can or should be written off as childish behavior.

I feel so bad for you. Do you have someone you can go to for support? There are usually counselors in school systems. I know school is out right now but someone there may be able to help you find the support you need.

Perhaps we need to know just what you mean by "having sex".

What were they doing?

Were they masturbating?

What does the other mom mean when she says her son was already having sex?

Many of us seem to have learned how to masturbate at about the age of 10.

From the first post I didn't get any indication this was two boys. If they were masturbating, that's quite common. From what you've added it seems they both knew what they were doing and were just doing it together.  When I was a boy we got together to do it just for fun and probably to see how the other guy did it. Like Taz I learned about it from a cousin when I was 10 also.

My mother walked in on me and two cousins masturbating in my room and all she did was say "supper's ready". Then she closed the door and left.

If that's what they were doing I really think you should try to change your feelings about it and let him know you accept it and it's nothing to be ashamed of or to feel guilty or bad about. If you can do that I think the bond between you and him will become much better.