How I tell him? What I do?

So I posted something early didn’t get much advice. But pretty much got told break it off. Here a little back story..

Guy came into my work for job interview. He got the job the next day I found out I was training him. He for sure was my dream guy look and personality just off the top!. We laughed, filtered, and just felt like magic at the time. He listened to me and all, something I have never had in someone. I played the hard to get cause really didn’t want date and just focus on school(I went thru a horrible breakup 10 months ago) just one day he offered take me out for lunch, I declined. Then next day my car ends up not starting(new car, but god had other plans!) he offered take me home and caved in! He ended up taking me out and time just passed and I didn’t get home until 10! Then just after that we went on few dates(just kissed and hug)was never official until the other day he asked me out be his gf... Will... when he did he told me he had heavy baggage. He got a daughter that’s 3 years old and one on the way. She due any day now. (YALL I WAS SHOCK CAUSE HE HAD CAR SEAT IN BACK OF THE CAR! AND MOVED IT TO THE TRUNK WHEN I WENT BACK TO MY CAR GET STUFF! HE SAID HE DIDN’T WANT ME ASK A MILLION QUESTION.. I don’t blame him🤣) He 20 and I am 18. I feel like to much for me to play stepmom. Im not sure, but I have been told break off cause so many reasons like...

The kids might get attached, you’ll get attached to the kids, what if the mom doesn’t like you convince him breakup with you, or it never feels like you guys have alone time.( cause the custody is 50/50. They have live in same school district for the kids and all this). Before anybody says How you know they aren’t still together Will 1. He said I could met the mom cause she wants meet me( she sounds extremely jealous! But idk why she one cheated!)

2. I have seen the message between them when she did cheat.

3. Yes new baby’s his. Cause she cheated 1 month later down the road.

Also the whole custody thing sounds extreme to me cause I don’t have kid. So ofc I don’t really understand. I told him I plan moving next year for college. He said if this relationship serious and runs smoothie(all sweeet stuff) he said he wouldn’t mind coming with me and finishing school there with me. (He does have his AS almost and plans on getting his BS and maybe more) I just feel like he leaving his kids behind and idk. My nieces and nephews father left. Had another kid. And never stayed in contact with them. I always feel bad for them. Soo. I for sure don’t want that to happen to his kids.

I just don’t know how explain him all this. I just don’t want affect us at work because we are partners at work. How do I stop catching feelings? Like what I do!? I feel like he starts see another girl I’ll be jealous... idk I haven’t made up my mind and I just need help!!

Sorry for this being so long.