Hello everyone,
I'm going through severe stress, panic and depression right now. However, my story does not fit truly into any of the categories here, but I guess "Relationships" sums it up best. I have high hopes in this forum, as I think I mostly need some guidance. Whoever takes their time to read all this and provide input - I will be so grateful for that!

What follows is the story of my life, a 20-something guy at a breaking point in his life.

Childhood (0 - 15)
My parents had a dysfunctional marriage. They divorced when I was 10 and that dragged on a few years. This left a toll on both me, my sibling and my mother.
Most of the time after that, we both lived with my mother and abandoned contact with our father. My mother, although she's a good person, become a 'broken' person. Personal and financial burdens took a toll on her, and she is hard to be around. She has very pessimistic views on life, but never complains. I however was always described as 'stable', and I took pride in overcoming such a hard fate gracefully.

Adolescence (15 - 22)
After I started living on my own I gradually reduced the interaction with my family as a necessary consequence of the distance.
My life finally took a turn for the better, I wasn't bullied (as in school) anymore, and by starting in university I could finally live a life that I enjoyed. However, I soon got depressed over the lack of a romantic relationship. It was fine for the first few years, but by the time I was 22 I was completely depressed about it. I lacked the self-confidence to approach women, and was at a point where I completely gave up on it. Somehow, at age 23 I ended up with a girl in bed - but I had to live with the insight that I had ED. Back then I had no clue what that was, but soon concluded that my sexual preferences were preventing me from having normal sex (since my early childhood, I have had fantasies of being submissive towards women, which rarely involved vanilla sex at all).

Near-Adulthood (23 - 26)
After my realization of not being able to function sexually, I began a period of self-improvement and finally pushed through with my studies. I think it was at this point that I decided to be a 'career person' and made gradiose plans for the future. I guess this made me more attractive and I had a first relationship at age 24 which lasted for over two years. During that relationship however, we were not able to have sex. Also, I knew from the onset that my girlfriend of that time was not 'right for me'.
Everything changed, when at age 26 I left her for someone I truly fell in love with. This girl had everything I ever wanted, was smart, good-looking, and had the same hobbies as me. From the day we got together we basically didn't spend a single day apart.
We moved in together - and instead of a great career I just stuck in a university job so we could be close to each other. With this girl, I was actually able to have sex, and everything seemed perfect for nearly 3 years.

Now (approaching 30)
By now, I know what co-dependence is, as that is exactly what happened to me. I used the relationship as a crutch to get over my insecurities and low self-esteem. I identified solely with the relationship, and all my social interactions were reduced to her circle of friends. I was just a +1 in her life - and I believe I was fine with that because of my sexual preferences. On the inside, she was everything to me, but on the outside I somehow did not show that at all.
Despite being 'happy' however, I kept complaining day after day. I was unhappy with not having moved away from the same old place, unhappy with my job, and unhappy with the people I had to see every day.

Fast forward to one week ago. She dumps me! My world has fallen apart and I can't make sense of the chips that remain.
When she told me how broken our relationship was, I was in shock and had a hard time believing it. But the more I think about it, the more I must admit that this is true. She doesn't want to be the only pillar of my happiness, and says she will be much better off without me. Worse, she tells me that our sex sucked, and she's off with another guy, who also is a common friend - all so cliché, and yet I fail to see any humor in it.
Now that this bubble of an illusion of happiness has bursted, I am back at square one. I feel tremendous regret that I have let the life I could have had slip by. The new guy will take my place, and live the live I could have lived. The few friends I have are all approaching their 30ies, and they are all single. But at least they have a career, having worked in decent jobs for the past 5 years.
As the clouds of relationship happiness are lifting, I have to face the ugly truth below: I am unhappy with my life, I screwed up my career, and I may not be able to ever get such a blissful partner again.

I have already come to the conclusion that now is the time to DO something, take matters into my own hands.
However, I'm still overcome by feelings of regret and panic attacks every few minutes. This has been going on for over a week now, and it does not seem to decline.