Hello Samantha:
I am so so sorry to hear that you are going through such a stressful, traumatic and conflicting time. And it is not fair. You, and your mother, do not deserve any of this, and there is no harm in coming right out and saying it. I hope your mother can get the medical help she needs, and does not allow herself to go downhill. I know you may find it difficult, but you are not superhuman, none of us are, and therefore you cannot please everyone, no matter how you try. I can only advise you, for your own sake, don't even try.
You say: "It is physically painful to think of him not loving me. " Yes, that pain must be great indeed, because "good enough" fathers do love their children and do not leave them in the lurch. And yet the recognition of that fact is the first step on the road to self-recovery and seeing things as they are. You deserve a normal life, free of the need to be everything to everyone.
Take care of yourself, Samantha. I wish you the very best
Seven