Oh, heavens honey, don't take what your father is saying to you as some kind of reason you are not wanted, especially not taking this to the level of thinking if you are not alive that would be helpful an any way.

I think what he really means is that because your mother has such a hard time getting around that he doesn't want her to feel obligated to fuss just because you might come for a visit. Yet, that isn't ONLY just about you, but it's more than likely how he would feel about having any company stopping by for a visit. The true bottom line is that he doesn't want your mother fussing and stressing. He is repeating it because anytime she fusses or stresses it just upsets him. It's hard to live with someone who has physical challenges like that. It has nothing to do with you personally.