Anybody who says that you can't sing and play the fiddle at the same time is simply not living in the same world as the rest of us. Plenty of excellent fiddlers do, and have done, this. In the UK I can think of Jim Eldon, Eliza Carthy and Tom McConville just off the top o fmy head. In the US it is a well accepted Old Timey style.
Go for it kiddo!