My Parent has ADHD

I understand this forum is primarily for marriage related ADHD concerns, but I couldn't find any other place to discuss this topic. 

  My dad has ADHD, although he has not been diagnosed, and will probably refuse to do so; he is 56. He has caused our life to spiral out of control. My family is in debt, and there is constant chaos.  His actions day-to-day lead me to feel as though he is not my father, but my brother. He is irresponsible, lazy, erratic, impulsive, cruel with his words, and unconcerned with the well being of our family; he only acts like a dad when it suits him, never when I need him to be a dad. My mother, on the other hand, tries her hardest everyday to make sure my brother and I have food to eat and house to live in. I try to help out around the house as much as I can, but my assistance is limited because I am just learning how to drive (I am 20!). It is incredibly difficult for both my mom and I to "watch over" a 56 year old man who acts similar to a beheaded chicken on speed. He fights with everyone constantly, but never knows when anything is wrong, does only what he wants to do, and doesn't care about anything anyone has to say. Worst of all, my older brother has Bipolar disorder and Epilepsy, so when you add him to the equation, the odds are never good. I have never had a chance to be a kid, because ever since I was 14, I was watching over the two of them (because my mom works two jobs, and is gone a lot). All of this is just the tip of the iceberg....I am simply writing on this forum to reach someone who understand what it is like to live like this, and to learn that I am not alone. I don't have any questions about ADHD, or concerns, I just would like to talk to someone who's been there. Thanks!