He lied because it was easier. That's not a positive.
Don't you think he's being careful how he presents the reality here? I think he likes the OP and doesn't want to put her off, but he also doesn't want to put off the mother of his child. I think he's totally mixed up.
How old are you, OP? And him? Sorry if I've missed that somewhere.
It all sounds to me like everything is first time here - first child, first relationships - it sounds like immaturity, inexperience, not knowing quite what to do.
Which indeed could make life miserable for everyone. The only way forwards, OP, is to try an all cards on the table scenario. If you like him so much, and he seems to like you, then I would say this gets one shot: make him feel he can actually tell you the truth without it being a big deal. Explain how him telling you exactly what the issues are is the MOST important thing if he wants to have any chance of keeping seeing you.
IF he's just all over the place and doesn't know how to deal with having had his first child with a woman he doesn't want to be with, but who wants to be with him, then IF you think he's worth it, your way forwards is going to be to work together with him on this. To support him. To help him get into a situation where he can see his child in a fair and reasonable way without the threat of losing that because he doesn't want to be with her.
[Note: a lot of people on here will now think I'm being at best idiotically nice, and at worst facilitating a lying cheating SOB who should fuck right off - but, you OP wanted advice and options, and that's what I'm giving you.]
IF you go this way, then you are going to have to park your worries on a shelf and trust him. Trust, crucially, his feelings for you.
But if he can't do it, can't or won't tell you properly, can't or won't trust you, then to be honest you're on a bit of a hiding to nothing. If he fobs you off or reassures you in a way that doesn't feel so reassuring, that would be much more likely to suggest he's playing the two of you, as well.
EITHER way, this isn't straightforward with him. But then it was never going to be, with a 1-year-old with another woman who still wants him.
Is he worth the hassle? That's really the question you need to ask yourself.