Oh god @Cinno you seem very fixated on dating & the fact that you'll never find a man.
That's the very least of your worries right now imo.
I think you could start a list like a previous poster suggested & start making small positive improvements. Action will make you feel more in control & that in itself will make you feel better.
You desperately need a social outlet for yourself.
What are you interested in? Reading? Join an online book club
Learning a new skill check out your local community college & perhaps there's a teen in your neighbourhood who would br glad of some early evening babysitting?
Do you have neighbours? Have one around for a coffee & a chat? Build a little bit of a network for yourself
I suspect you'll come back to say you live rurally, don't know any neighbours, no teens in your area etc
Which i think brings us back to the same point again which is that you seem like you could use some therapy or meds to help you out of this dark dreary place & to help you realise life is for living & you only get one go at it. And that every single decision you make or don't make has a profound impact on your dc. You're literally imprinting a blueprint of life on them. We all are with our children so we have to make good choices for them.
They need to see you having a good life. Not ground down by the burden of having had them & being left with them