Your opinion doesn't really matter, it's what the law thinks. Contrary to what some people might think as common sense, I was on a course recently and what if you had an intruder in your house while you were in bed upstairs cropped up. The answer was, if you went down and ended up assaulting them you would be in trouble because you could have stayed upstairs and kept yourself safe. It may sound bonkers but that was the advice.
Edited to add. If you were assaulted first, or under threat of assault, then it's reasonable to defend yourself proportionately to the threat, but no more than that.