Am I a bad son to my father? Please read.?

I have not always been the best son ever but ever since my dad split with my mother I couldnt help but deal with the guilt that I was a terrible son. I know he expected better from me, to be educated, to be loving, and to be obedient and respectful but instead when i was growing up i was always rebellious and always shouting back at him & now im 20 and i always hang out with my dad to make up for them yrs that i was never really appreciative. He has a new family (a girlfriend with 3 kids) and they all love him like crazy, especially his girlfriends daughter who is 15. She calls him dad and she always plays with him and jokes around with him & tells him she loves him, but when i was that age and over i was the opposite. Yesterday all 3 kids bought him a fathers day gift with love, and he was real happy but me i couldnt buy him a gift since i didnt have the money to buy him one yet. I feel like a bad son and last night i cried and thought of suicide because i cant deal with the guilt. I wish i could start over.