I want to come out but i cant.

I am a 16 year old guy that lives in the UK. I am already out to my grandmother, well i didnt say to her "i am gay" I wrote her a note that i was going to give to her but at the last minute i pussied out and left it under my bed where she found it a month or so later.Now my dilemma is i want to come out to my grandfather. I dont know how he will take it though. For examples when there has been something on the TV with a gay person or couple he has said something like "hes/they're poofs"Maybe he doesn't mean anything homophobic by it and its just because he was born in the late 40s. He doesn't seem to have a problem with other members of the family that are gay and when a family member came to stay at ours with her girlfriend he didn't look like he cared about the sexuality.I was just sat downstairs with him watching TV and tried to say the words " I am gay" but i just couldn't, i wrote it on a piece of paper but i was to worried to give it too him,i was sat shacking i just couldn't tell him. Part of me hates having to live a lie and not being able to be myself but then i am too much of a pussy to tell him.I hate it.Can anyone suggest anything to help?