What's normal to feel in situations like this ?Is it okay if I hate my mom for what she did ? Is it okay to love my mom despite what she did ?

What you're feeling is difficult to handle, but that doesn't make it abnormal (and there's really no way that you 'should' be feeling- take it from someone twice your age, you'll get further in life by listening to what you do feel and working with it than trying to figure out what you're supposed to feel, even when it's really fucking confusing like right now).

You can love someone and hate them at the same time. You can feel like you're supposed to hate someone and actually love them, and vice versa. You can still love someone and resent their actions and their selfishness in taking those actions. You can long for the good times and have it hurt that all those memories get tainted.

You need someone to talk to. You tried reaching out to your father and your sister, and they're both occupied with their own processing right now- I suggest starting with your school counselor, and depending on what you find there, maybe asking your father about therapy. Therapy isn't something I'm suggesting to say you're broken or there's something wrong with you- I'm suggesting therapy because it's somewhere you can go and say "I hate my mother, why can't she keep her goddamn legs closed" and "I love my mom and I miss her and I wish we could be a family" in the same session and no one will judge you for it. Therapy is a chance for you to have to worry about no one's feelings but your own.