Have a virtual hug from me.
I was single full time working mum for 20 years.
My two lads moved out last year to independent lives so it's been hard, but I seem to have succeeded in bringing them up happy and healthy with limited support
They used to go to their Dad's every other weekend (although that petered out to barely seeing them at all by the time they were teens). The rest of the time they were my sole responsibility.
I was fortunate to have supportive work where they excused me from any work trips/training outside if working hours. They were accommodating to unpaid leave when ds2 was in hospital with asthma etc.
I had good wrap around childcare that covered holidays (expensively) as well.
It was tough, I'm not going to lie, but when there's no alternative you just get on with it.
Am glad I was able to continue working as I've now paid off my mortgage and looking forward to retirement in couple of years.
My ex is an arse, and although he dumped me, in hindsight it's been easier to parent without him. That's definitely not to say it's been easy.