I feel doing it alone can be a very positive thing.
Yes it's hard, but it can be a positive thing.
The way I see it, is with not having a partner around or a relationship that is negative. You have all the more love and attention to gives to your kids. You can give so much more of yourself to them and also they can be a great comfort and support in a time like yours.
You can just look at them and go, wow, what a great job I have done bringing these darling children into the world.
I wouldn't know how to conquer things if the children are old enough to understand that Dad is maybe not going to be around. All I know from what I've heard is just make sure they know in no way is it there fault. As kids just seem to blame themselves which sucks, as it's so not their fault.
I wish I could give you big HUGS!
Stay strong and look at your children in you feel down and they will always do something to make you smile. Or else give them a big hug! Hugs work wonders