Such a complicated situation involving the guy I like and my friend

I am here because I feel I can't talk about any of this with any of my local friends, as you will see why soon. I have been dealing with so much internalized anxiety, angst, and frustration over this whole situation. I could really use some honest advice about what steps to take so that I no longer have to live in such turmoil.

Here goes...

A couple of months ago I joined a gay yoga class at the invitation of my friend, David. This is my first class, and it is really hot out, and the water jug is empty. I go to the front desk to ask if there is any more water, and I hear a voice say "You can have some of mine!" I turn around and I see the most handsome guy, it was instant chemistry. I accepted his water and class started.

So after class, we all go out to dinner. At the dinner table, I learned that this guy, we'll call him Mark, was doing a triathlon relay with a couple other guys there, one of them being my really good friend, David.

The next week we all go out to a piano bar after yoga. At the piano bar, we all sing in front of everybody. Mark sang Hallelujah by Jeff Buckley. It was so beautiful. Then after the piano bar, four of us went across the street to dance, one of them being Mark, and one of them being David, and myself, and another. We had a great time dancing! On the drive home, I was listening to my iphone, and it was in shuffle mode. I have over 3,000 songs, and one of the songs that came up on my shuffle was "Hallelujah."

So now I'm thinking a lot about this guy, and have developed a huge crush on him. I plan on asking him out and fantasize about how I am going to do it. It has to be in person, I tell myself, don't do the text or facebook thing. And I probably would have built up the courage to do it, to, if it wasn't for this devastating bombshell:

My friend David tells me he has a crush on Mark.

Now, David and Mark have known each other a while longer than I have, so immediately my heart sinks, for I know I can't do anything about this guy I like because I don't want to risk my friendship. I start going into shut off mode- I close up and shut out all the excitement and memories I had in the brief moments up until then.
But my biggest fear was Mark liking him back!

Now, at yoga classes, and dinner, I am a bit more distant with Mark. I don't look over at him as much, I don't engage him hardly at all. But every time I saw him, it would open up the hurt I felt a little more. It was bliss and torture to see him every week.

David eventually told Mark his feelings for him, and then Mark declared he didn't have those same feelings back.

Which is what I wanted, but I still feel so awkward and uncertain around him. And I am jealous of my friend David, because he has such a good bond and friendship with Mark and they are always hanging out, and I want to be the one taking Mark out, but because of this whole situation, I have been pushed into a corner and have my feelings and heart totally denied. I can never get any time alone with Mark to say any of this, for my friend David is always around, and I don't want to hurt him, especially since he was rejected by this guy.

But it still hurts to see Mark. I don't even want to go to the yoga class now or hang out with these new friends because it hurts to see him, thinking I can't do anything about the situation but sit in a fantasy world where none of these complications that ended up ruining my love interest happened.

I don't know where to go at this point. I don't want to drop out and avoid life. But I also don't want to keep living in this hell.