Lots of sympathy,this is an awful time to split.
It happened to me when I was pregnant with DS.I was 3 months pregnant.
Although I knew my marriage was over,all I wanted was the security of a "loving" relationship,to bring our new baby into.
It was having the baby that "brought me to my senses".
I realised he would new be the father my baby needed,and I couldn't keep "covering up" the missing bits in our relationship anymore ,now I had different priorities.
Six years later I met and later married my now DH,and we went on to have 2 DD's.
It wasn't easy on my own,but I had a good reason to make a good life for us,my DS.
I am happier now,than I could ever have been with my ExH,and was surprisingly quite happy on my own.
Sometimes,as in my case,its a blessing in disguise,when you look back,as having a dependant bundle that needs you,helps you realise that you and dc are entitled to so much more.
Once your baby is born,you'll be able to look to the future,and meet someone worthy of you and your baby's love.