What do you think about the fact that I've been depressed for years and I've arranged to speak to my male best friend about it tonight?
Why have you been so depressed?
I am worried what he thinks about me.
It's a good thing to seek help when you are feeling depressed, but it's important not to overwhelm other people with your problems. I am sure your friend wants to help, but everyone has their own issues, so try not to overburden someone. Seeking a therapist to help with your issues would be a good idea to help you feel better.
I am not sure if it's a good idea.
It seems like you have a lot on your plate, but a professional would be able to help you so much more than a friend you've known. While I'm sure he would like to help, he can't make your depression go away and you need to understand that.