Did my dad give me good advice?

I'm having a tiff with a couple of my second cousins (my dad's first cousins). I know time will heal this eventually; however, I was having such a hard time with it mentally to the point of suffering from ill health. I talked to my dad for over an over about it and he said he was in a similar mental state when it came to his stepsons (who are drug addicts) where it would bother him real bad, too, and my dad told me that one day he just stop let it bothering him because he realized he was only hurting himself and he said the next day, it was "like a light switch came on" and since then it has not bothered him. I am trying to follow his advice (about 95% successfully, as women do tend to internalize things more than men). He also advised me to keep my email messages to them "light and airy" and not to "stoop to their level". Do you think he gave me good advice? (he has before)