STD? Is it possible?

I’ve been talking to this guy. We just hung out and we always have consensual sex, as long as he uses a condom because I’m not birth control. I was giving him a hand job and we decided to go to the back of the car to do it. So I’m laying down and we’re kissing and i feel him trying to go in WITHOUT a condom so I told him “wait put on the condom” and he was like “nothing is gonna happen” so i freaked out and started to push him off and i kept telling him to get off me to please get off me because I’m not with it. He eventually got off me. But I’m worried. Since i was already giving him a handjob, is it possible precum could get me pregnant? i mean he was only in me for like less than 10 seconds. I don’t think he really came. And another thing LETS SAY HE HAS A DISEASE HE DIDNT TELL ME ABOUT, is it possible for him to give it to me although he didn’t go all the way in? It was just his tip for less than 10 seconds. I’m seriously freaking out.