DISEASE

hey guys this might be stupid but it's always good to ask questions to be safe. My boyfriend has been away for a while but we have never gotten so physical yet but I'm scared if he might have a disease he's not slept w two there girls but I don't know how many blow jobs he has gotten, he wants to rub his dick on my clit but I'm scared of any diseases is it possible if itsjust rubbing or only if it goes in