Oh, Op, you poor thing, you have had such a hard time lately, I am not surprised you feel battered and bruised by life. But the thing to hold onto is that: your son is with you and all the lies and crap they told was proven to be not true.
I do see why you want an independent career and an independent life. I would post asking for medics to tell you what they do if they don't do medicine, as lots of ideas will be out there, I'm not a medic so can't help you on that score.
I do think though, that being an academic is a very long and probably not a very fulfilling career move though if you feeling battered and bruised. If you want to do a Masters for interest, fine, but doing a Masters and a PhD and trying to get a job afterwards is not for the faint of heart at the moment, there are far more people with PhDs than with relevant well-paid permanent jobs. You would probably end up in 8 years time with a 1 year post-doc with no permanence, nearly half the people in the sector are on contracts. It is taking much longer to move on to permanent posts than it used to do, so the chances of becoming a lecturer/professor are fewer. Sorry to sound negative, and perhaps you will be that person it works for, and I do know someone who was 50 when she started her PhD and has found consultancy work, but she was not reliant on it as a full income, which you would be.
Can you not restart your cleaning company with someone else doing morning shifts? I hear there is huge demand for cleaners, and it's hard to find good workers, but it might be more straightforward.
I think being dependent again on your 'sociopathic' father is a very bad idea and I can't see the promise of a golden career at the end of it either to be honest. that doesn't mean you don't have good career prospects, I would imagine there are lots of jobs in medicine which aren't so people- oriented that might be open to you.