Now here is something I have a good deal of personal experience with.My mother and I NEVER got along when I was young. When she wasn't screaming at me, she was hitting me with her hands. When she wasn't hitting me with her hands, she was using other household objects to beat me into submission. Yup, we're talkin' some pretty serious abuse here. If I knew then what I know now about child abuse...I would have gotten myself the heck out of that house before I got myself killed.
So with that in the background, I was unable to have the relationship that I wanted with my mother. My younger siblings (two, then three, then four) did not seem to have the same difficulties. For some reason, my mom chose me to slap around. As a result, I decided to fight back. I made her life hell. I would argue with her, and put up a fight when she would attack me.
Eventually, the beatings stopped. But the yelling continued unabated. I gave it right back, determined to do battle with my mom until she left me alone. This vicuous cycle continued for years.
Then it stopped in a hearbeat. On March 10, 1995; my brothers and I came home to an empty house. This was not unusual, since my mother attended various School Board functions that kept her away from the house until the evenings. But when she had not returned by 8pm, we got worried. At 8:30 that night my father and mother walked in the door at the same time, and herded all five of us into the living room. She calmly told us she had been at the doctor's office all day. Because I was a smartass, I said, "Okay, what are you dying of?" After a brief silence, she answered, "Breast cancer."
So you can imagine how low I felt after that one. At that point, the entire nature of the game changed. I decided that I was going to live every day as if it was my mom's last one with me, and that I was going to show her how much I truly cared about her.
For the next thirteen months, I realized that my mother and I had a lot in common. I lamented a bit over the time I had lost, all the years of fighting when really we were just flip sides of the same coin. If I had just controlled myself and not been such a problem child, maybe things would have been different. But either way, I only remember fighting with my mom once after her diagnosis. And in the middle of the argument, I looked at her and she looked at me, and we both said, "What in the hell are we fighting about?" 
She died on April 26, 1996. While I initially felt like you did, that I had wasted precious time fighting with her, I had to realize that we had finally found the relationship we both wanted with one another...even though it was at the eleventh hour.
I am sure your Grandmother, like my mom, would not want you to dwell on past problems. When we are young, we tend to lack the foresight that we attain when we are older. You certainly cannot be blamed for things you did when you were not able to understand their significance. I treated it as a lesson learned, and I vowed not to take things for granted any longer.
I don't know if any of that helped, but I sure hope it did. Losing someone who is close to you is never an easy affair, but sometimes there are hidden lessons within each painful loss that we can take with us to make us better people down the road. This is one of them.
Dust, take care of yourself. If you feel like you would like to talk about it, please feel free to contact me. And feel better soon. 
[This message has been edited by BruinDan (edited 09-26-2002).]