I agree with everyone else in that he was cheating on you, and this whole 'You're not ambitious enough' was a cover story for leaving you for her.
@TheHerboriste Hold on......you're not expecting women to juggle & handle everything that Oldglasses pointed out AND also have a full time job???
Also agree with @ThreeLocusts . Maybe he was disappointed that you weren't contributing as much financially what he'd like, but at the same time, some men don't really know what they want from a woman. I wonder if that applies to him too.
A part of them wants her to be the sort of stay-at-home housewife mother figure as that makes them feel good and dominant.....but then they also find it a turn-off as fundamentally they don't respect what women do in the domestic sphere.
It also requires them to be the breadwinnner, which means that if they're not particularly generous generally, as people, they'll be really analysing carefully what their money is getting them. Unless everything is perfect and they get their way most of the time, they're prone to getting resentful and feel the woman is sponging off him and taking advantage of his good character.
Those conflicted men are also prone to that because they want someone more 'ambitious', someone who matches the high regard their hold themselves in, some who matches their own success.....but when they get that, they feel emasculated and a little envious that their mates' partners are more domestically orientated.
For the time being, his girlfriend will fulfil the later need, but I wonder how long it will take for the shine to wear off.
Also, it's irresponsible and emotionally insensitive to introduce his girlfriend to your daughter this soon. That's a red flag, and shows he's incapable of understanding the way that children think & feel about these scenarios.