I bottle my emotions inside. How do I overcome this?

I think I'm too nice sometimes. I don't like confrontation. There are a lot of things my dad parents do that I don't like and I think is very weird. My dad does this and it really pisses me off is, he goes into the bathroom to pee without turning on the lights. He leaves the door half open or wide open at times and he just pees and it's annoying. I have my own bathroom, he uses the hallway bathroom and it really irritates me. Why doesn't he close the damn door. No one wants to see him peeing and its not like I see anything because it's dark and no windows but still close the damn door. It's just the right thing to do. He is cheap, maybe he is conserving energy and water by not turning on lights when he piss and peeing with the door half open so he can see but I think it's ******* gross but I'm too nice of a person to say anything. I keep everything on the inside. I don't have a good relationship with my dad so I don't feel comfortable talking to him.