"My DH has now decided that he would much prefer I become a SAHP as he has really enjoyed me being off on maternity leave. ... my DH thinks I am being selfish and thinks I should put my daughter first."
I realise the thread has moved on somewhat with further info, but these two statements in your OP just leapt out to me, whattodo202000. The first is truthful (he really enjoys having 'staff' doing the drudgery for him), and the second is an attempt at just plain blackmail.
He things he's got you trapped now
. That switch flicking as soon as you daughter was born, he's so sure he's got you trapped he thought it safe to drop the mask he's worn until now. You don't know this man. He looks like the man you married, but sadly, that man doesn't exist. He was an illusion spun by the selfish bastard squatting in your life. The man you see now is who he is, who he always was, and who he will always be. I'm so sorry
. But it will save you a lot of time and heartache if you accept that this man WILL NOT CHANGE into the man he made you believe he was. He will not change his ways. He will not step up. The man you see now is who he truly is.
"I think deep down I am embarrassed by what he has become and the fact we have not been married that long (just over 2 years now) so would feel like a failure if we got a divorce sad."
Do NOT be embarrassed! Too many women have stayed in bad marriages for that non-reason. For starters, you have nothing to be embarrassed about. You got played by a skilled operator, there is no shame in that. There WOULD be shame in sticking with him now the scales have fallen from your eyes.
So don't be embarrassed. Be grateful instead.
Be grateful that he overplayed his hand and moved too quickly. Had he kept his mask in place, shared the parenting, pulled his weight; well, he might have been able to persuade you to have a second child 'close together in age so they can be friends'. He might have been able to persuade you to abandon your career to achieve this. He might have been able to maintain his mask until then. Until you had a toddler and a babe-in-arms and no career to go back to. Instead, he pushed too hard too fast, and as a result, you - you have options. You still have a career. You have a supportive mother. You have somewhere to go. You have options.
I'm sorry you're going through this, @whattodo202000. It's shit. But it will be a lot shitter if you cling on to the fantasy that he will change back into the man you thought he was. He was never that man
. He has always been the man you see now.