Is it normal my mother punished me in unusual ways at home?

I grew up with a single mother as the only child. During my upbringing, she would use different ways to punish me. It didn't involve that much pain, but was humilating to various degrees. Up until adulthood, she would make me lie across her lap with my butt bare, and spank me with a hairbrush.If I protested, she would just do it longer. Whenever I was sick, she's take my temperature in the butt also. Everything like I was a small child.

The most tyrannical thing she did, was sitting over me and peeing in my face whenever she was really mad about something, in order to "put me in my place" and showing "who is the boss around the house." Once she did this for no reason at all, and told me she just felt like it. I wasn't allowed to turn my head, or she would hold it still for me, so everything would end directly on my face/lips. She'd then get up, tell me to clean myself, and walk out. In the worst period, this would happen weekly.

I don't live at home any longer, but whenever I come to visit for long, I'm afraid she'll do it again. She says that as long as I'm at home, I play by her rules.

I realize this is abuse, but I don't want to report my own mother. I want to tell her it will never happen again, but I'm not sure if I can, as she always gets mad/cold/tyrannical whenever I stand up to her.

The thought that is nagging me, was her motives for doing this in any way sexual, or was it just to control me?