Am I just a replacement? Or is he true?

It was Love @ 1st sight (literally) we always tell eachother how we love eachother & want to spend the rest of our lives together. He's a really sweet & caring guy......But,,,,, he recently came out of a 5 month relationship 6 days ago!! I think it's very fast & unusual to go in such a deep relationship, whether it be love @ 1st sight or not. & his ex seemed to be happy,,, until she asked me if i was dating him she rolled her eyes and laughed like it was funny and then she said "dont fall too fast" Now i cant help but worry if i'm just helping him recover from his previous relationship.... Plz Hlp! i need to know if i'm wasting my time.