I'm So Sick Of Waiting

I'm turning 30 in 2 months time, and am so tired of waiting to meet someone. I fell in love at 18, and we eneded up together for 6 years afterwards (all through my college days). Then one day he arrived at my house out of the blue and told me he had met someone else - just like that - no explanation - and disappeared out of my life. That was back in 2005, and I literally have not met anyone since then! Ok fair enough for the first year I couldn't bear the thought of being with anyone else, and had no interest in meeting someone. For the 2nd year, I enjoyed being single and had some fun. But after that I tried to meet someone new... and 5 years later it still hasn't happened. I'm getting so fed up, and tired and lonely that sometimes I don't even think I can go on. All my friends and workmates are getting married (I have 4 to go to next year - alone) and it's just so hard to keep smiling and being happy for them, one after another, while wondering if I will ever be the one people can be happy for.