superJj:
will i fry things up?
Quite likely. You power the devices with the appropriate voltage, not current. One has to wonder why you would want to do this anyway, so some clear explanation of your intentions might be in order. As things are, the Pro Mini is very probably redundant. If you must use one, why not use a 3.3v version? It would make far more sense to to have DS18B20 connected to one MCU and that passes the data to the other.