Ali, you certainly have been soul searching and I do completetely know how you feel. Honestly I do. I felt the same about my x and we had a lifetime together for which I shall always be grateful.

I believe / hope I may find love again. It will not be the same but it can be as good if not better.

I also agree that you should tell him face to face all what you have written. Now that will take ever ounze of courage you posess and the biggie is are you prepared to do that and accept whatever it results in.
I feel the time may never be right because of xyz. No time will be right if you only want one result.
Right now you are far from ready for that imo!Yet how can I know that. You may have that courage and deeper reserves than we can possibly know just from reading your posts.
Part of what prompted me to be so bold was as others have said just reading your posts.

You say you have never dated you just fall in love and end up in a relationship-I get from that rightly or wrongly you are impulsive and sensual (not purely sexual-I think there is a difference)
Also you are not a youngster(apologies) your body clock must be ticking loud and clear if you hope to have a family. I think you have made reference to this at some stage.
It takes time to build up most relationships, go through the preliminaries and then onto long term rel. /or marriage and then start a family.
Maybe better to hang on to what you know and love/need, than to risk losing the hope and have to start back at day 0ne.

Ali,I get the impression your bf has always had depression in some form or other and you can live with that or you can make a difference to it.
What you cannot live with is the fact he just left, no arguments you said, just gone.
You have put together all the missing peices by putting dates together bits of info gleaned, comments secondhand from others and the astrological info. You need the reason straight from the horses mouth.
How do you suppose this will come about.

One last thing is that all the things /qualities you ascribed to your x that you love are actually in a lot of people, you just haven't met them yet.
The bottom line is how to you confront a person who is conflict avoidant and runs for the hills?
You cannot make him profess his love for you or tell you what a huge mistake he has made,she means nothing to him etc
YOU can tell him HONESTLY in plain english, all senteneces finished, i's crossed and t's dotted so as to leave him in no doubt how you feel.No thinking he knows this, he has heard it from friends etc, No wriggle room, no if onlys after the conversation but to do that you have to be prepared for whatever answer he gives whether you like it or not and no back up plans to explain away his answer with reasons why he said it but just a willingness to accept.
Acceptance now that is hard.
Sorry for the long post but I was moved by your answer and I don't want you to feel I have negative thoughts about your situation.