Thank god you are not married to him. You aren’t, are you? No way should you risk him having any claim on half your assets, as he would in a marriage.
Normally I would say it is reasonable for partners living together and bringing up kids to come to whatever shared finances arrangement suits them, and that means joint responsibility for home upkeep etc etc.
In your case I would keep him at lodger status because you don’t want him to be able to claim he contributed to The house in any way that gives him the basis of a claim.
All this is because he has an ongoing gambling addiction.
That in turn makes him something of a cocklodger and only you can know if that is acceptable to you.
But first and foremost protect your home and your assets, for your kids’ sake.
He may we’ll argue that the reason he doesn’t contribute more is because he doesn’t co-own the house, but if he really wanted to co-own as an equal partner he could have pro actively looked for ways to do that, paying towards it etc. He has held in to his money and financial independence to keep his habit under the radar.
Bloody hell, he gambled away £52k that YOU ended up paying for 😡
It was also deeply dishonest to enter into a committed relationship with you without disclosing his addiction and debts.
And he has been dishonest again.
I gave up 8 years of my life to an addict of a different kind. He wasn’t seeking professional help, it all got worse and worse.
He is dishonest, he is a cocklodger .
You have worked hard and built your life around your kids’ needs. What example is he setting them?