Yes, we cope because we have to. Like any other parent, you use the time and resources you have available to you to do the best for your DC.
And we're not one homogeneous bunch you know. There's so much variation in terms of how many kids you have, how much support you have, how much you earn etc etc.
I have a fairly easy ride to be fair. Despite being an arsehole when we split up (he left me for another woman) exP is a good dad and a good co-parent. He has DS two nights a week and does childcare other nights. Crucially, I have someone that I can discuss issues around DS with someone who knows and loves him like I do and I know that's something a lot of single parents miss out on. I also have good family support. I have a part time job that pays well enough. DS is a fairly easy going child with no health issues or special needs and I am mostly healthy myself.
One of the hardest bits is the loneliness. I found the evenings tough at first when DS was small and went to bed earlier and I had no one to talk to. No one to share a "DS did a funny thing today!" story with. And going out to the park or for days out, just the two of us, and seeing "proper" families with mums and dads etc used to really sting...but I couldn't give a flying fuck about that now!
It's also tough being the person who does EVERYTHING. All the cooking, housework, DIY, admin...all down to me. I am very organised (partly by nature and partly because I have to be!) and somehow or other most things get done.
And I miss DS when he's with his dad. Some of my married friends are jealous of my childfree time and while I do usually enjoy it, I didn't choose not to see my child every other weekend
I do like the independence. I like being able to date! I now have a lovely boyfriend who I've been seeing for 4 months or so and we are having a great time going out a lot, and doing lots of fun thing. When I was with exP, we got stuck in a rut, like lots of parents of small children I think, and rarely went out.
And I like the relationship I have with DS. We're our own little family and we're very close.
So yeah, it has it's ups and downs but most people's lives do surely? A parent with a child with special needs, or lots of children, or with health problems, or an abusive partner or any numer of other things is going to have a much harder time of it.