If I was in space and died would my body decompose?We mean if you were simply inside an orbiting space habitat, or if you were actually literally in space with nothing between you and the vacuum?
Inside a space habitat, there are enough bacteria present in your body already that it would probably decompose in more or less the normal manner. Of course, any other astronauts inside the same vehicle wouldn't be ready to just let your corpse lie around and stink up their precious air. They'd probably put the body in a bag and send it down with the next cargo ship so that your family could spend a few hours crying over it.
On the other hand, if you were actually in space, then the decomposition process would occur to some extent, but it would stop before very long. The bacteria, exposed to the extremes of temperature and radiation in space, would not have enough energy available to keep on thriving for all that long. Most especially, they would tend to survive only inside your body, leaving the skin more or less untouched (this would have the strange effect of rotting much of your insides while leaving almost no visible mark of decomposition on your body's surface). Once things got too nasty for them, some of them would go into a dormant state, which unfortunately for them would last more or less forever, resulting in their eventual deaths. Depending on where you were in the Universe, your body might also be broken up by other processes; in Earth orbit you would over the period of a few hundred years be torn up by debris impacts, and if you were anywhere inside the area of the Earth's orbit, the Sun's energy would cause your body to eventually break apart through heat (this would also kill all the bacteria somewhat sooner than would otherwise be the case). Out in interstellar or intergalactic space, on the other hand, your frozen corpse could conceivably last in a recognizable form for millions of years.