I don't believe for one bit that the mom stabbed/threw a knife at tonya. During the TV interview, tonya couldn't figure out on which side of her arm the knife hit.... and... she didn't show the scar. Usually people pull up their sleeve to show where a scar would be.
Again during the interview, she was shown a photo from a yearbook. tonya had an attitude because the photo was also used for competitions. I don't think the mom could afford a separate photographer for promos.
I found tonya to be heartless, ungrateful and a spoiled brat who did need to be spanked. If the mom was a "B" it is only tonya was a handful. She worked 3 jobs, raised other children and still had time to be at the skating rink for practice.
Haha yeah Tonya was all that!