It doesn't feel it was a decision coming from a "flip of a switch". From what you write, it has been brewing and festering. It is more an accumulation of things. And she took you at your word when you mentioned divorce.

Good that you take accountability re not being there as much as you could and that you are now trying + you want to make it work.

It seems unfortunate as it seems there is miscommunication, lack of communication, things said in the heat of the moment... and it has snowballed as a result.

Could you ask her to give it one more try to 'save' the marriage, especially with a little one? To both give it your best shot (going for couples' counselling to help with communication issues, not sulking but talking, respect, being there for one another and *hearing* one another). IF she refuses to try, unfortunately, it is her prerogative - again, not knowing what she is feeling/thinking. Though, another argument for her to give it a go is that a couples' counsellor would hear 'her' side (so she would feel heard?) IF she feels unheard in the relationship.