Should I be worried about my dad?!?

Okay, this is a kind of long story, but to make it short, my dad is bipolar. My parents are separated and I live with my mom. He's sent us $150 over three years, which is pretty much enough to pay our cable bill for a month. He always makes excuses for not remembering our birthdays and not visiting, and he doesn't take medication and drinks, a lot. His house is in foreclosure, and he just left his animals there. I sent him an e-mail because I was really pissed, but I know it wasn't the best idea. I was IM'ing my cousin at the time (from my dad's side) and he started TALKING to her as I was. He was saying things that were scaring her, and that pissed me off SO much. I was going to chew him out, but after she copied and pasted what he said, I decided not to. I'm guessing he was manic and now he's progressing into a psychotic episode (a break with reality). He emailed me after talking to her, and it was gibberish about hw I'm always speaking bullshit. Should I be worried?!