In my dating years I went on one date with a guy who had no involvement in his biological child's life and eventually gave up his rights so his ex’s new spouse adopted the kid. He shared it on the first date which was quite brave of him. I could see that technically speaking he isn’t a father and really has no kids as his kid has two parents and it’s not him. So I could see how someone wouldn’t even share it if they gave a child for adoption.

Did he give up his child for adoption? If not did he explain his lack of involvement?

Did you ask him why he decided to share it now? What changed?

You sound very young. You’ve been with this man for only a year and a half and you love his children “like your own”. I really don’t think it’s the case. If you break up now you likely never see these kids again and you’ll eventually move on and won’t spend your life suffering not seeing them. That’s absolutely not how it works with “your own”.

I think you should be done with this guy. Date slowly, don’t move in, get to know people first, don’t get involved with their kids right away or maybe don’t even date men with kids (you are young and have many options) and don’t try to get pregnant so soon after meeting someone and not even being married