I feel that you’re getting moral and emotional fairness mixed up with what legally is possible and advisable. It’s all shit, you thought you’d be together forever and that your investment into the relationship was caring for the children. Unfortunately the law is looking at it as kids are adults now, you’ve got your equity, get a job or claim benefits. If we were your friends sitting having coffee, we would no doubt be appalled for you and calling him a bastard for doing this to you. Right now we’re trying to help you understand your position and to get through it mentally and get your head around it.
When people on here say marriage protects you, that’s because when you’re married you then get said equity, pensions etc but the broader benefit usually applies to people with young children. Marriage helps prevent you from getting turfed out on your ear with little kids in tow. You have to understand while, as much as we all understand you want space for your grown up kids to stay over, legally there’s no ‘reason’ as they have their rooms there and are on the way to independence. To have no overview of the finances and to not work or claim PIP etc at all anyone on here would have always said you’re still very vulnerable.
Stop focusing on feelings, I know it’s all really painful, but they are irrelevant right now. It’s about what you can convince the legal system to consider based on law. You’d need some kind of probable cause and/or a forensic accountant to start digging into his finances. Ie. You’d need to be able to say ‘he’s hiding a pension from X because I remember him paying into that when he worked for Y from 2015-2020’ because having a feeling about it and assuming it’s been frittered away are not solid evidence.
How severe are your 18 year old’s SEN in terms of long term care? Does he get DLA, have a diagnosis etc? Because only then would he potentially be considered as they do a child in terms of shared care. Otherwise, he’s voted with his feet and gone to dad’s place, from mid teens they consider where the child wants to go and pretty much unless there’s massive issues abuse etc they let them give their input. Do you get PIP and/or ESA for your condition? More forms if you haven’t got these already, but you need to strengthen yourself financially going forward.
Unless we get a rough idea of details nobody will be able to give better advice. If your equity gets you a 1 bed and him a 3 bed with a mortgage, that is fair under the law. When me and my EXH split, he wanted a bigger place for when the kids visit, which he could not say when would be and refused to be locked into childcare agreements, they were primary age. Everyone said absolutely not, mum (me) needs a full sized home to house them, dad will have to make do as he’s not the primary parent.