Why cant I just let nature take its course?

I have been in a relationship for most of my adult life but after my last one ended I said that I wanted to just be single, now I dont want this. I have fallin for the first guy that I went out with have only be single for about 10 months. But now I want to be with someone that doesnt care if I am alive. I hate being by myself an feel like time is running out!! Do you guys think its true that there is someone for everybody? My ex told me no one will ever love me, that they will only use me for an my money. I feel he could be right!!!