birthday

My dad was born March 4th, 1939, the youngest of 12 kids. His mom was 51 when he was born, and his dad was 76. He was an uncle to a 12 year-old at birth. He was the tallest of them all, and the first one in his whole family to attend college. His brother who was just older than he was died when they were kids, as did his father, so in a lot of day-to-day ways it was just him & his mom. I wonder how she felt on this day 69 years ago, welcoming her final child, the one who would turn out to be vastly more devoted to her than any of the others. I'll never forget once saying to my father, in a teenage know-it-all snitty snotty moment, "Nothing lasts forever." His eyes welled up and he looked straight at me and said, "That's not true. I have loved my mother every day of my life." It blew me away because he didn't usually say things like that, and he rarely talked about his mother. She died suddenly, three days before I was born.

How?

A friend was just told that his dad has only a few weeks left. I want to be there for him. But the situation is eerily close to my own experience.
It's bringing up all sorts of feelings of sadness and self pity that I've worked so hard to limit in my everyday life. (They tend to surface on special occasions like weddings, birthdays, and Father's Day.)
How can I help him deal without reliving my own painful experience?