Which Family Member should I tell first?

I have already told most of the people that matter at school about my homosexuality (not bisexuality, I think that they think that I'm 100% gay, but i am bisexual, but that doesn't matter) and I confidently tell anyone who asks.

But now I am thinking that I should let my family know about my bisexuality, however I do not know who to tell first. It may seem obvious to firstly tell my parents, but I just think that I shouldn't. Not only may I change to straight (I know it's unlikely, but it's possible) in the future, so it may not be worth telling them now when I might change, but I will have to live with them for the next several years. So it may become quite awkward and it just wouldn't be the same, do you know what I mean? Also, my parents seem quite (not extremely) homophobic, so they may not react well.

Let's move onto my grandparents. I would be slightly more comfortable in telling my grandparents (my mom's side only though, as my dad's patents are EXTREMELY homophobic). However, of course, there are negatives. They may be homophobic, it probably will be awkward, and they may not take it well overall. I'm not even going to mention my dad's parents, because I know for a fact that they are very homophobic and would not take it well at all. That bad that they might fall out with me, and not want to be a part of my life (yes, it's that bad), so they are out of the question.

Finally I have a cousin (she is quite old though, something like 65 years old, she's like my 6th cousin), we are very close even though we don't see each other that often, but she seem like she's all for equality, and I think I can confide in her not telling anyone, and it would not be awkward as we don't see each other that often. But I still think that I should tell someone closer to me.

What do you think? Who should I tell first?:

- Parents
- Grandparents (Mom's side)
- Cousin

Also, what should I do of they take it badly?

Sorry for the length, and thanks in advance for any advice you could give.