Another non-dad but . . . I actually think your DH should cut the cord if he wants to. Yes, the cord is the physical connection between me and my babies, but I saw my DH cutting it as a symbolic joining of him into the relationship I had previously exclusively had with my daughters if that makes sense.

TBH I never thought about cutting the cord myself - I was upset when DH initially said with DD#1 that he didn't want to do it. When the time came my OB just assumed he was doing it so DH clamped and cut both our girls' cords. He really enjoyed doing it and I loved his involvement.

Having said all that, if my DH had behaved the way yours did during either of my labours I would have chucked him out - of the delivery room at least and quite possibly my marriage. That is absolutely unacceptable as far as I'm concerned. Given his past performance you definitely deserve to overrule his wishes in preference of your own (and not be selfish in doing so) and have your mum there for support. I would also put your DH on notice that unless you get proper support from him during the birth this time he's out and you will cut the cord yourself.