Sorry to hear about your problems, OP.
But the world is a varied place and people have all sorts of experiences and reasons for what they do.
In my extended family there is a definite correlation marriage-longterm happiness, cohabiting-less stable relationship, but I'm not stupid enough to believe that this is because marriage makes us happy. I think it's simply that those of us who did commit to marriage were already in relationships that were or had the potential to be steady.
Also, in the case of myself and db, they were relationships that required a lot of commitment, including one partner moving a long way: it would have been a risky thing to do if we had not already felt very sure. There were also in both cases immigration issues which made this a complete non-issue: either we got married or we waved good-bye.
I also think dh and I were very fortunate because we were both the children of happy marriage, my parents were the children of happy marriages, there was a lot there to see and learn from. Our expectations were high and I really believe that was a good thing. Reading Relationships I am often flabbergasted to see what low expectations some women have and how they seem to believe that they are single-handedly responsible for every atom of happiness in a relationship. That can't be right.
In any case, the fact that there are many happy marriages doesn't mean marriage/longterm relationship has to be the only way to go. I know plenty of happy children raised by single parents. And many women (and men) who only seem to come to life once they are out of an unhappy relationship.