Depressed!

My husband and I have one child together and for months he was practically begging me for another child my gut instinct told me that it wasn't a good idea as our relationship was rocky and I even told him that for months he was such a perfect husband and I decided we would have another baby as I thought he had changed. I ended up falling pregnant and his now left me (12 weeks pregnant) and I can't help but think that I am a complete idiot. I am keeping the baby and I will raise the baby to the best of my ability on my own he wants no contact and nothing to do with either children anymore but it's just so unfair!! Men can up and leave and go back to normal life GOOD mothers cannot, and I don't want to I'm glad to be a mum but I can't help thinking how unfair this is and how depressed it's making me. Sorry I needed to let it out!