Hi there!
Oh Goodness, monophobia... yes. It was my worst symptom for a while, just dreadful to endure. I couldn't quite understand what was going on as it didn't feel like 'fear' per say, it was just... mental torture. So obviously I would dread finding myself alone because of how dreadful it would make me feel, and yes, I would panic, but fear in itself, no, it wasn't quite the word. With hindsight, I think it might have to do with a mix of mental akathisia and a total lack of emotional drive or direction: when I'd find myself alone with mental akathisia, there was no way I could escape the mental anguish, I'd feel as if I was going to explode. But being with people would help me distract somewhat from that hell, I'd also 'feed' on their own emotional direction ('I want to do this or that') so could (somewhat...) escape that horrible void inside me.
For me, monophobia faded gradually but it sure did. Now, that doesn't mean that all you can do is sit back and wait for it to pass while you cling to every family member who can spare you some time! That's a horrible situation to be in because you depend on others, you lose all power on the way you feel... and that is a horrible feeling to add to the rest of the horrible feelings brought on by the symptoms and the situation in itself. No, you have other options, other tools are available, you just need to find what works for you. They might not be optimal solutions but they will bring more options to you, options is the word :thumbs-up: For example, my monophobia was the reason I enrolled in evening classes again and joined lots of Meetups (meetup.com), in spite of feeling no desire for anything. I just went. Dishing out lots and lots of willpower every single time, going through the motions in spite of the absence of joy or interest. I started going to group workout classes and yoga, I also did some volunteering, and goodness what else. I tried so many things during those hard times! Anything to be in a group for a couple of hours and tide me over into the evening hours when my brother would come home from work and we'd have dinner together. Until he left off for 3 weeks in Australia! That was another big step, but it was possible because I had started developing my coping toolbox

And knowing that for 13 years on drugs, I was more or less passed out on a couch hidden behind a closed door and had stopped answering the phone. Those classes were the opportunity to make friends, and let me tell you that I now have some really wonderful friends I met during those times! So what I am saying is that this symptom is indeed horrific, but you have the strength within yourself to use that bastard to your advantage!
You can follow my journey through monophobia on my blog:
http://www.benzobuddies.org/forum/index.php?topic=124608.msg2468479#msg2468479 (this was the first post I think where I wrote something about feeling deeply tortured when alone, the journey was all to begin...)
Keep fighting and know that you have everything within you to get through this phase of recovery :thumbs-up:
Best wishes,
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Keep fighting