Please help, is this healthy parenting?

I'm 17 and my mom has got some issues I think. In the past my dad left and she handled it horribly- we would get into fights and she'd hit me and stuff. One time when I was little she hit me in the face "by accident" and made my nose bleed. She didn't mean to do THAT, but she still meant to hold my mouth shut or something. I don't know...
And now, just tonight, we were arguing about my dad. She doesn't hit me anymore, but the first thing she did when we walked in the door was grab the newspaper and hit the dogs with it because they were jumping on the door. She's kind of mean to our dogs now, she curses and swears at them when they do something bad and calls them names or tell them they're stupid. She practically bares her teeth and growls.
She's ALWAYS talking negatively about my dad. Yes, he left. Yes, he's living with another woman and her kids... but she makes it sound like he's killed or murdered someone. "Go find out for yourself!" She told me tonight.
She puts me in this position for far too long now... I'm done going back and forth between "Who's the good parent this week?". Please help. Is my mom good? Or is she just plain mean? Thanks. Sorry this is so long.

It's not very good parenting, no. It seems like she is so mad at your dad that she doesn't realize that you still love him as a father, or that she can't cope with that fact. It's quite normal for people who are abandoned by their partner to get bitter and resentful and this sometimes is taken out on the kids. But that is unfair! And she has HIT you, which is unacceptable no matter what. She probably wishes you cut all ties with your father and took "her side", but she can't demand that of you just because her feelings are hurt. I think that is why she gets so angry at you. She needs to realize that even though he left you he is still your father and you want to stay in touch with him, and that she's acting a bit selfish because she puts her own hurt feelings above your well-being.

This is kinda exactly what I feel it's like and exactly what I've been telling her. Although I shouldn't... but thank you for the input, it was very helpful.