Stepmom is a PITA!

tay • TTC for baby one with my amazing wife. Married 2 years. Together 8 years.
My stepmom and I have butted heads for the 10+ years I've known her. She has this obnoxious personality that drives me insane. She's always spoiling her teenager and forcing my dad into financial struggles because she just "NEEDS" a computer or the latest iPhone. She's lazy and my dad is doing everything around the house while her and her daughter sit around!! We couldn't be more opposite. Her newest thing is pushing my buttons about politics because she's a diehard Republican while I'm very liberal. I have more class than her so I don't sink to her level. I just ignore her or laugh it off because I don't like confrontation but she thrives off it!! I love my dad and spending time with him. I've stopped spending as much time with them because my stepmom just completely frustrates me. My wife and I are TTC and I know once we have a baby, she is going to push herself more into our lives and frankly, I wish she'd go the F away. 
Anyone else have an annoying stepparent or in-law? How do you deal with them?!