Something Cheerier Than The Usual

I've had a crush on my best friend for a long time.  The problem is, they're seeing someone else.

They said if circumstances were different, we'd be dating.  The circumstances are, we work together and...  Their best friend had a huge crush on me in the spring, and it was mutual.  Allegedly, they still have a thing for me, but they are a lying piece of work and I'm not interested in dealing with all their immature bullcrap.  So my work bestie wants to respect their friend and leave me off-limits. 

I just wish it weren't so.  They're one of the awesomest people ever.  I want to share everything with them, good and bad.  I can always count on them for good advice or a laugh.  I can't imagine work without them; they help me get through everyday.  They're funny, have great taste in media, and are all around pretty cool.  They're also one of the kindest, most generous people I know.  I have a ton of respect for them.

So...  They're seeing someone else.  I am legitimately happy for them.  It makes me feel better about life when good things happen to good, deserving people.  I hope all the best for the two of them.  

Just...  What do I do in the meantime?