Hindsight, blah, blah! Yes, it would have been nice, but, let’s deal with the reality.
You actually sound pretty sensible to me OP. You’ve read the writing on the wall, you’re not playing the ‘pick me’ card, so, time to pull on those big girl pants.
You’ve already contacted your old employer, so you’ve made a start. The trick will be to line those bloody ducks up as fast as you can. If the old employer can’t give you a job, ask them for a glowing reference.
Sort out your CV. Run it through AI for tips and tweaking. Update your linked in, send the CV off to recruiters and follow up with calls. One of the best things here is that you do have some decent earning potential. When you do start working, get onto that NI and sort your own pension plan out. My mum was a single parent, so while I have four kids, I’ve always worked full time as the importance of standing on my own two feet was drummed into me. You may not love being a lawyer, but it pays better than cleaning toilets and sometimes you’ve just got to do what you’ve got to do. If you need wrap around care for the kids for a while, make sure the ex is paying half of this.
Find all the paperwork and hire a shit hot lawyer. You say you can’t afford it, but as a lawyer yourself, you should know that you also can’t afford not to do this. This about how you would advise your best friend.
I’m sure that you’re hurt and devastated, but for now, time for a bit of anger while you sort out the practicalities of getting through this. Going back to law will get you through, you can always change careers again later, but for now, play all your skills to your advantage. You’ve got this!