Hi. I've had my share of single parenting. When DH & I were younger with DD1 we split up for a little while. I was baisially a single mum right up til then, as he had no interest in DD1 at all & really had nothing to do with her. It was really hard knowing he was right there, but had no interest in her at all. Since we had DD2 he is completely different coz now he can see what he missed out on & he's finding it really hard to get over it, coz he doesn't have a very good relationship with DD1 even now. It's getting there, but it'll always be hard.
Is your mum a good support?
Right now I feel pretty alone too as DH is away working & is totally unreachable. I'm not single, but I am doing it alone right now.
It is hard, but I think you'll find that when you get over the pain of losing your relationship, you will enjoy it. You will be able to put all your energy into your kids & raising them without needing the extra time & energy for him. You'll be able to do what you want when you want with them without having to worry about anyone elses opinion.
It will take a while to get over him, but I believe that it's for the best. You don't want to be with someone that doesn't want to be with you. Thats not fair on you. Get out & enjoy your life.

Good luck.