resentment

Shona
Longish post just need a rant 
Had my son 3 and a half weeks ago, first week or so my partner was helping out, getting up through the night with us, even though he was weakening at 5.30am to start work, now in the last week he hasn't gotten up/helped and not really done much when he gets home, Ive already told him I'm in fumes as I'm so tiered with getting up in the night and dealing with our baby and my 4 year old. 
I feel pretty lonely and feel like a single parent half the time,  I have spoken to him about all this but doesn't seem to be making a difference and I'm now beginning to resent him, he asked me to marry him days after our son was born, and I said yes but now I'm beginning to change my mind and struggle with wanting to be with him (sounds harsh I know) 
I pretty much do everything, from house work to dealing with the boys to shopping, I'm done in mentally physically and emotionally, no amount of nagging seems to work, im ready to sit in a corner and cry, he doesn't seem to realise how much it's taken out of me looking after 2 children a house and him. 
Just don't know what to do anymore 😫