Best Friend Issue

Ok my best friend opened upto me on facebook regarding a matter he made me promise to keep to myself so i won't disclose what was said. He has a habit of revealing things when high (he smokes weed) or drunk. This particular matter actually isn't as suprising to me as i thought it would be since he made roundabout references to it before. I did however provide a supportive response and affirmed that i would be there for him nomatter what. From here i'm not sure what went wrong as he has deleted facebook and his other forms of contact. I don't have a phone number for him either as he constantly changes sim cards. We live in different counties now so it isn't easy for me to go find him as i don't even know his address. I approached his sister on facebook just explaining that i need his number for an important matter and that i'm a little worried about him. She basicly quoted his age saying he's a grown man who can sort any problems he has by himself. I find that quite obtuse but i didn't want to cause an argument so i let it drop. I do have very serious concerns over this matter because he has a family and this issue he has could ruin all that. If he actually blurted this out to me while under the influnce then he could be really scared at it being revealed and i'm worried he could do harm/kill himself. What should my play be here? Go find him and have a one on one and reassure him his secret is safe? Or leave it and hope he just needs space? I'm actually getting stressed not knowing the right answer. I don't want to make things worse but i also don't want to wake up one day and find he's commited suicide and i did nothing to prevent it.

Hi, if he is your best friend he probably already knows you have his best interest in mind. Is there anything that happened that makes you think he would try to harm himself?

In regards to this specific friend there has never been any self harm issues but i can say he has the capacity to overreact in situations and has displayed erratic behaviour. There is a memory of a more distant friend that commited suicide after witholding a secret so that has stuck in my mind which is why i quoted similar concerns in this thread.

But anyways to update i have managed to make contact with the person in question and he has basicly said everything he can that the revelation was a joke made under the influence of alcohol and drugs. I didn't go any deeper into it and played along with him to make him more comfortable. I can't see any reason to bring it back up if he doesn't want to talk about it.

Since we live hours away from each other we hardly hang out so i have suggested that we take a vacation home/abroad together. He has never left the UK despite owning a passport so i'm hoping that invite will give him something positive to focus on.