Lonely Widow ready for love unsure how to find it.?

My husband (the love of my life) died when I was 29. My kids were 8 and 4. they are grown now and in college 23 and 18. I re-married 6 years later because I wanted my children to have a father, I loved him at first but was missing my husband that died I have been dating but am getting very discouraged. My first husband that died it was a once in a lifetime love but I know that there has to be someone out there I can fall in love with. We were together 15 years. I keep wondering if I will ever find someone else to love and spend the rest of my life with, the prospects are pretty poor right now. I feel so sad. I am trying not to give up. I envy other people that have someone. I would like anyone that has been in my position to give me advice. I don't even know where to look for a good man. I have been just sorta waiting for it to happen, but that's not working. I am an independent professional. Any ideas?