Is bipolar disorder an excuse?

Okay so I could write alot about this. Basically my father cheated on my mom and left our family. He was completely irrational and delusional during the whole situation, blaming everything on my mom. A week later he called my mom and said he wanted to come back and fix things. My dad is bipolar but has had no huge outbursts ever since he started his medication a few years back, until now. He came back but he did not seem okay. He was shaking, he was saying weird and very judgmental things; the guilt was definitely crushing him... but he was still blaming things on my mom. He found out my mom made her own bank account (because he left her) so he started ranting on at my mom saying she betrayed him and cussing her out (obviously ridiculous). My mom was scared so she was just crying and saying sorry. He turned around and said to me "Looks like you're mom's starting more problems again" and I felt I needed to defend her so I said "No, you're the problem" and he freaked out. He charged at me, kicked a chair at me, and pushed me, my mom started pushing him back as he tried to throw punches. He yelled "I'm gonna kick your f***ing ***" and "wanna go buddy!?" (I'm 17). I was waiting for him to just hit me so I could hit him back but my mom started pushing him so he started kicking and punching things and he threw a chair out the window. He then continued to cuss at us and threaten us and started to pack his bags to leave again. He continued to make a scene and he left. He then sent me a long text the next morning saying he was so sorry, that he loves me, and that he really hopes i will forgive him one day (he still hasn't apologized for breaking up our family...). I keep ignoring his texts because I'm angry but should I be more understanding since he is bipolar? Is being bipolar an excuse for any of this? Lying, cheating, deceiving, violence, extreme selfishness? sorry for writing so much i could actually write on forever on the story