I strongly identify with your feelings - I know that place very well.
Here is the way I hacked it out: 1. Regarding relationships with girls\friend - After years of having too many friends, I understood that almost everyone I met wanted to be friends of mine, this lead to an overload of friends, and made me be not a good friend of a lot of freinds. Once I realized that, I decided to stop socializing with everyone I met, and focus on my closest friends.
Another hack regarding friends - I found that having a certain structure, like meeting every thursday to play poker and playstation - was really good for me.(Of course that I socialize beyond this routine, but this baseline routine with friends really made our friendship strong and fulfilling).
2. Focusing on one thing: I found that working with partners really helps me focus, it is true regarding learning, programming and founding startups.
If you wish to create a new startup - find a partner and make it with him\her - level out with him that you have a focusing problem - and that he should call you out if he sees that you are unfocused or unproductive.
this is very powerful, this discovery has changed my life, it allowed me to open my startups, and today I am the owner of a very successful israeli bootstrapped start up(founded with 2 partners ofcourse).
3. hacking suicide thoughts\meaningless feeling - most important hack of all - imagine being a mountaineer, climbing on the everest, your feet hurt, it is difficult to breath, it is cold, but you still do it because it is your fucking dream.
Now image climbing the everest without a special reason, without having the dream of climbing it - the pain would be the same, but you would hate it so much, it would take so much energy from you, you would be miserable and stop pretty early on.
My point is, my friend - that if you feel that pain overwhelms you - you are currently climbing the wrong mountain(You don't have a burning desire).
You should stop climbing(trying to focus, trying to better yourself, trying to do things) - and decide what is the thing you really want to do. You might not know, you might have some options and you won't be sure which is the "right" dream from you, I can tell you this, life is precious - you should be brave(taking the risk of maybe it is the "wrong" dream) and choose your dream - and fucking go for it full power. Even if in the end you will understand that you didn't "really" want to do that dream, the only true way of finding out is doing it fullpower.
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If all fails - I highly recommend finding a life coach, I have found that they are extremely useful, not trying to figure out whats wrong with you, but just giving you power to do the things you really want to do(and finding out what these things are).