I'm also terrified of snakes. I live in Louisiana, so I've learned to deal with them (but still don't like them).
I've never seen a live snake in one of the parks at WDW, but I keep my eyes peeled for them ( I know the kind of places they like to hide out). We have seen live ones at EVERY SINGLE WDW resort we've stayed at. We're used to always having to watch where we walk and know to avoid certain places, so we're rarely startled by one.
I'm also pretty good at judging from a safe distance whether or not they're poisonous. Believe it or not, it can make a difference in your reaction to them.
The fake snakes in the attractions don't bother me that much. I pretty much know where all of them are and I can close my eyes if I need to. Having had to deal with so many live ones in my lifetime really makes the fake ones seem kinda silly.