Ah ktgirl, I remember when we first moved DS to his own room. We had the monitor turned all the way up, just in case we didn't hear him, and would race (literally running) down to him at the slightest noise... Half the time it was just sleep noises. And the monitor was soooo loud it startled us awake so I'd be sitting there, heart pounding in my chest as I woke up. Now we have it all the way down on the lowest setting and wait to be sure he's really up before going down there.
It really took some time to get used to sleeping separately - it just felt so wrong. Honestly, if the cot had fit in our room, we'd have moved it in. As it is, I'm back sleeping with him now anyway .
Anyway, give yourself some time to get used to it. And if you find yourself lying awake thinking "oh, i hope they're ok....", just slip in and check up on them for your own peace of mind (otherwise you'll just lie there worrying....like me)