He has gone away for several weekends a year . . . I've never stopped him but apparently he has felt guilty leaving me
User1488
So he "feels guilty" about leaving you for the occasional weekend, but not for dumping you for the rest of your life?
I'm sorry User - he is making excuses for being a selfish bastard. He is blaming your reduced mobility for his decision instead of taking responsibility for himself - this way it's your fault, and he, big-hearted guy that he is, has done all he can but it's just tearing him apart so he can't continue.
What. A. CROCK!
I suspect that he has a lady friend tucked away somewhere - this is a terrible thing to say to you OP, but I think he's probably been continually faithful to you for some time but has now decided he doesn't want to have to skulk around.
Don't beg him. Tell him to bugger off, If your home has been adapted to account for your mobility problems, you have a very good argument for staying.
Get as much information as you can regarding finances etc, and contact a lawyer asap - get in touch with the CAB if you can't afford one, and have a look at the relationships thread on this forum. there is a lot of good advice.
As others have said, although this is devastating for you, in a year, or two years, you will realise that it is the best thing that could happen to you. YOU will be the one who has their freedom back, not him.
He has behaved like an arse - don't get upset, as Scorpis has said get very, very angry!