Separation while pregnant...

Hi guys, I need some comfort support and help from all that have been through this or is going through this... I have been with my husband for almost 4 years. We have a 2 year old and I am at 39 weeks pregnant and about to have the 2nd any day soon. I've decided on a separation and a divorce after the baby is born. My husband seems to be bipolar and has his moments and honestly through both my pregnancies have managed to make me severely depressed. I find that there is no more happiness and that I must find a way to move on. The thing is I feel a lot of guilt with my children... I just don't know.. I have been reading on how to cope with this and realizing this way means my children will never have a whole family with both parents together. Something I always vowed to stay away from as much as I can because I came from a broken family and know how it feels to not have a father and a whole family.. I mean I grew up fine with just having my mother there but there was always a tiny empty spot there... I'm trying to learn to cope with this hurt inside my heart... Any advice would be helpful as I have already told my husband I wanted the separation and I also promised myself and told him I wouldn't go back and forth about this... He hasn't answered or said anything but I really feel like my minds been made up on this topic.. Did any of you mothers go through the same thing and how did you cope? Please help...