Have namechanged for this. It's really an AIBU but I'd prefer not to get jumped on 
Bit of backstory. Will try and keep it simple! Xh and I have been divorced for several years. We have tried to maintain a functional, civil relationship for the sake of ds and generally we have managed. Ds is now 10.
However, xh has always (long before our marriage) had issues with drink and (to a lesser extent) drugs. It was part of what broke up our marriage. Last summer, after the break-up of a long-term relationship, he went off the rails and ended up in rehab. He has, apparently, been attending AA since. He lost his home and has in the last 12 months lived at several different addresses. It has been a very difficult and unsettling year for all of us, ds especially. Xh has lied a lot and been very erratic and unreliable. It's hard to trust him.
Over Christmas, xh went home (overseas) to visit family. He came back a few days ago and immediately said that he wanted to take ds back with him for a holiday at Easter.
Whilst he was away, he posted photos on the dreaded FB of him in bars, what he was drinking (def not non-alcoholic!), 'lovely' barmaids etc! ie. he is clearly drinking again. (He also posted pics of him out shooting with his family, including a 13-year-old cousin of ds's. He says he would not want that for ds but I'm not sure I believe him. The thought of ds anywhere near guns scares the living daylights out of me!)
Ds has visited his family overseas once, but that was when xh was in a stable relationship with a girl that was very 'sensible' and caring for ds, and so I felt quite secure that ds was in good hands. I want ds to have a relationship with that side of his family but don't feel that I can trust xh at the moment to take ds to the other side of the world.
AIBU about this? I would be happy to reconsider next year but just feel that it's all too soon. My trust in him, and his sense of responsibility, is simply not there yet, imo. Or am I just being controlling?