This is not very easy to type, but this is my personal opinion. 2 decades ago, you met your current housemate and made a commitment with her. Maybe not a marriage commitment, but a commitment nonetheless. You moved in together, and had a relationship. Her son having children, from what I understood, was what began to tear you two apart. Firstly, taking on her son's children should have been discussed beforehand. Obviously there are things that can not be forseen in any way, but that is something huge. Since she just assumed you'd be fine, a discussion would have been better. However, since this(I think) is HER home,(correct me if I'm wrong) then it really wasn't your say, unless there was some kind of stipulating contract.
This is my point: you made a commitment with her. Moved in together. She now depends on your disability and food stamps. You have lived with her for many, many years. To up and leave, just because you feel you have the right to love, is wrong. You should have weighed the consequences to the idea of moving in with a woman who isn't the go out and get a job type. Since you had feelings for her back then, and probably thought those feelings would be there forever, you went ahead and moved in with her. Now you're also disabled, and she can't get work.
Obviously the choice is yours. In my mind the first thing wrong with this is that you moved in with her in the first place, without marrying her, because now there's no accountability to your relationship. What probably COULD have been a salvagable relationship, isn't any longer because there was no binding. Hence the reason you went looking for love elsewhere. Which is the second thing I see wrong. Because now you're faced with a completely horrible situation. You feel you have the right to love, but the woman you're housing with has the right to the same thing. Wether or not you think it's possible(and it may not be possible) the right thing to have done BEFORE finding love in another woman, would have been to try and reconcile. I think you should still try and reconcile. NOTHING is impossible with God.
Now, you have feelings for another woman, yet another problem, only she lives in Israel. I DO NOT agree with your moving there. In my opinion it would be a completely selfish thing to do. You have, however, already reserved a ticket. And the choice is, ultimately, yours. I'm very disturbed that you care more about hurting a woman you've never even met in person before, than you do completely abandoning a woman who can't even provide for herself. Which do you think you'd hurt more?
You choose, of course, but you came on to get other's opinions. This is mine; stay where you are. Try to reconcile your relationship with the woman you're with. There was obviously something there that brought you two together in the first place, so there's no reason why that can't be rekindled. As hard as that may be to accept, I would say to try it. Pray and ask God to reconcile your relationship. Nothing is impossible through Him.