win
I am totally confused as to what the OP's husband does that makes it unsafe for her. It sounds like this is about the garden. I appreciate you love your garden, but how does he make it unsafe for you. Does he do things indoors as well, or is this a case of picking your battles, once we start seeing faults, it gets deeper and deeper very quickly. Could you perhaps remind yourself what is is or was you really loved about him, which made you want to marry him and then look for that more than his faults, unless his actions really makes life unsafe for you. Your poor GS must sense the atmosphere in the house. There is I am sure, a reason why he lives with you, he should be happy with you, feel safe and be in a good family atmosphere. How old is he?
This is all about compromise, what he likes and you like, at least you are now talking about it, and can hopefully do so in future before any changes are made. It is his home too, so he has to have an input both to indoors and outside arrangements obviously, as you do.
I would be more concerned about the moving aspect, this is where I think you need help with explaining to him why it is so important you move before it is too late. What would he do if you died and he had to downsize by himself. Perhaps ask him that question, and you certainly have to face the same one. One of you will go first, the other one left sorting everything unless you do it together whilst you can, with help of course. The garden will not matter then, so please try to accept that the garden is done, but you will not be there for long anyway, then concentrate on getting the downsizing on the map instead. Good idea to gt help in as support for yourself, but socially and an extra pair of hands around the house, would OH like that?