Every child no matter what their parents have done to them wants the love of that parent(s) and I think that is the case in your situation. Your mother and your sister can't understand that because of what he did to all of you especially sexually abusing your sister, they still feel resentment for the treatment that they got from him. Since you are an adult it's up to you if you want to forgive your father for his actions in the past. I believe people can change if they make the effort to change and that includes some counseling to figure out why he did that in the first place and if he asks for forgiveness. You may want to ask your father why he has never apologized to your mother and sister but apologized to you. Explain to your mother that you don't want to live your life hating him and that hating him isn't healthy. Tell her that you have come to grips with what happened to you and you choose to forgive him rather than spend the rest of your life hating him. Ask yourself if you would trust your children around him by themselves and what ever your answer is then you will find your answer to your last question to me. I also think that you and your mother and sister need some counseling also maybe even family counseling together. Just don't expect your mother and sister to have the same forgiveness that you have had because they may never be ready to do that.
No you're not wrong for loving him nevertheless he is your father and did give you life even though he didn't make it such a happy life he still give you that gift so of course you are going to love him. You may have reserved yourself to the fact that you do not want to turn around one day and him pass away and you still didn't forgive him and then that would be on your conscience that is your decision and your mother and sister don't have to agree with you but they shouldn't make you feel in a way that you don't feel comfortable feeling. I think you and your mother and sister should agree to allow each other to disagree about this subject and let it go and possibly don't tell them when you do talk to him because it brings up more resentment from them.