The age old question, should I stay friends with my ex? Like most situations in life, there are pros and cons to this, so let's take a look at them...
You will probably be tempted to have sex with them from time to time which is probably more of a problem than a good thing; no matter how drunk or horny you might be, sex complicates friendship.
Seeing your ex with somebody else will be even harder if you stay friends because there's less chance of avoiding them.
It might take you longer to get over a relationship if you have little to no escape from that person. Just imagine, seeing their face in a cafe, seeing their face in the club, seeing their face in a pillow, seeing their face formulate in the milk with your cereal...
There will always be those things they do or say that you will find annoying. Who knows, they may have been one of the reasons you broke up in the first place!
You will most likely 'secretly' want them to fail in at least some aspects of their life. They are your ex after all! Having that secret, underlying negative energy is probably not a great thing to have in a friendship, even if you aren't aware of it.
If you worked well as friends before you got together it's great to remain friends, who doesn't like friends? Especially if that person is important in your life anyway.
You can avoid some of the nasty, bad break-up venom and hate if you stay friendly.
Those gay social circles can be small. Being friends means you avoid the whole awkward 'avoiding each other' in public places routine.
Isn't it kind of nice to know you always have someone who you know will look at you naked and think "nice"?!
They probably know things about you that you don't even know or notice about yourself. This may come in handy in many situations, like when you're thinking of dating someone else. Having a friend that's like "no you can't date that seafood enthusiast, you have a thing about oysters!" to which you reply "oh yeah, I forgot, thanks bro". And the day is saved.
If you broke up for reasons like "we were in different places", "I needed a break" or "I had to travel and move around a lot" who knows, maybe you could work it out again in the future, so staying friends seems like the sensible choice.