So I do not think that you have wasted the whole 10 years but you have wasted the time since he proposed and then flaked till now - that time you have wasted (I have wasted 15 years on my ex H so I get to tell other people that they are wasting their time

). He is not a little boy. He is 53 - set in his ways. I know this age - my ex H just turned 54. What he has been doing he will continue to be doing. Extrapolate from the past experience with him. There is not point in prolonging this experiment - you have already obtained all the (negative) results.
Yes, I think it would need to be online for your socialization because where else these days?
As to what comes first - finding a man or finding a depression treatment, I first found a depression treatment, and started seeing people only when all depression was gone. But it was a very brutal road for me, and one I would not have been able to travel completely alone - my online friends (Anika, for one

) have been there for me. So - not entirely alone. Socialization itself is important to counteract depression. For bipolar, there is even a therapy called "social rhythm (or rhythms - unsure) therapy". So maybe you do not have to first deal with the depression and then with socialization - maybe you can deal with both at the same time.