I would NEVER dangle a live prey item by its tail, clamped in a hemostat in front of any of my collection.
You've taken a an otherwise relaxed prey item and immediately made them fearful and on the defensive and more likely to lash out.
I've fed over 15K live prey items off. I've never intervened in feeding and I've never had any of my collection have problems effectively dispatching their prey without injury to themselves.
I only offer well fed, well hydrated prey, and I drop them in the opposite end of the enclosure as my snake and let the snake kill it however it prefers.
If your snake will eat three mice in a row, then keep doing that. When I first started keeping ball pythons, I was also scared to move up to rats. Now that's all I feed, other than mouse hoppers to new hatchlings. Get a rat that's 2 x the size of a mouse to start with - your snake will be fine.