I'm going to lose it!

So I am currently 9 weeks pregnant. I'm tired, so tired all the time. I have a 15 month old son who was breastfed up until about 5 days ago. Well he has been waking in the middle of the night crying. When I go in he will fall back to sleep in my arms but the minute I lay him down he starts crying again. I am exhausted. I have tried to just let him whine and cry but he works himself up into full blown crying and screeching.

My SO works full-time. I'm a SAHM and go to school (didn't go this semester due to extreme morning sickness). From the day we brought our son home I have always been the one to wake in the night for him. I have never had my SO wake (mostly because I breastfed and it seemed pointless for him to lose sleep when he works fulltime). Well now I just can't cope with having to constantly get up and try to put our son back to bed. But my SO won't get up to help. At all. He tells me to just let him get up. Like what? Right now it's 5:52am and I have been up since 3:30am trying to get my son to stay asleep. He fell asleep at 4:30 and I got 15 minutes of sleep before he was up again at 4:50am. At 5:30am he went back to sleep. The minute I layed back down in bed he started screaming. My SO told me to just let him get up. So now I'm up for the day. My SO is still in bed until his alarm goes off at 6:40am.

Am I wrong for being frustrated? I really want to cry. And I'm starting to resent my SO for being able to just sleep and not let our son wakong phase him.

I have also been so sick with extreme morning sickness and my body just feels drained.