Cherish the time you've got with both parents. I haven't lost my parents; however, the "sperm donor" lives accross town about 5 minutes away from my house. We've n-e-v-e-r spoken. Kinda weird at times, since I see him often. My thinking is that he walked away and is not interested, maybe I'm wrong...
Luckily Mom married a great guy who has been very supportive in all ways possible. Really the epitomy of a true father. I hate to think how I'll feel when something happens to him. The other guy, it's hard to mourn someone you don't know.
Anyway, take advantage now, while you can. Happy Father's Day to all!