I very much agree with what Snooky said.
I appreciate his mum is sick and needs extra help. But disappearing for 3 weeks, is not normal.
He has a responsibility to you and your children, so raising it as a concern shouldn't be dismissed.
You need help too.
The fact that he belittles you when you put up a post with yourself, is actually pretty gobsmacking.
Your hormones are all over as it is, you don't need someone being negative and demeaning to you. You deserve more!
At a point where your mental health needs to be nurtured, it's not being. You're at a very vulnerable point and every bit of support is needed.
I would suggest sitting down and really weighing out the pros and cons.
Would it be more stressful to continue as is, once baby 2 is here? Or would it be more stressful going solo?
If it helps, I'm completely alone and pregnant, the whole prospect terrifies me.
But what matters to me, is that I'm healthy and the baby is healthy.
You need to be selfish. Do what's right for you, not what you think is right, just to keep peace.
Theres increased mental health services for pregnant women, so if you need someone to talk to, just have a look for your area.
Sometimes it helps talking to someone who doesn't know your situation.