op, it is true that many people do realise that they're in the wrong relationship when they meet someone else, but invariably it is the meeting not the person which is the catelist for the ending of the relationship, and these further relationships rarely go on to become anything more.
It sounds as if this man may well have been in an unhappy relationship, and that meeting you was what triggered his decision to leave his marriage, however given that he doesn't want to make anything permanent with you yet suggests that now he has left his marriage he realises he is free to be on his own and to decide what he wants from life.
The line that "they don't see in him what I do" is the oldest cliche in the book. Yes he may have some redeeming features, but ultimately what you see in him is what you want to see, the man who makes you smile, who made you realise what has been wrong in your previous relationship, the man who "gets" you like no-one else, and all of those things may well be true, but what your friends are seeing is a man who has played both you and his wife for the past year, lying to you both, sneaking around to be with you while he decided whether or not to leave his wife, keeping you hanging on to make sure that you would still be around if he does leave, and making sure that you stay around in case he decides it's you after all.
Op you've never actually had a relationship with this man yet. All your encounters have been on stolen moments, based on infatuation and nothing else. You may love each other, but that won't be certain until you have actually been together as a couple, where you are free to be together.
Even if you had got together a year ago and were in a year-long stable relationship it would be too soon to have a baby. Bringing a baby in to a relationship which as yet doesn't actually exist would be insanity. If you wanted a baby you might as well just go to a sperm bank and find a suitable donor, but given you don't actually want a baby you should just enjoy your freedom.