this sounds like more of a deeper rooted thing. If you scream when someone goes near your vagina to insert something or freeze up, it sounds as if you have been sexually molested? There is no need to respond to that although if this is the case, it sounds as if you need to address that before you will be able to allow anyone into that zone, with you.
If that is not the case, then there is still something going on emotionally that you 'scream or tighten' up when anyone goes near that part of your body. It needs to be addressed as well.
You were so well 'primed' by using muscle relaxants and alcohol along with lube, that it would appear lovemaking would have been very easy to do. This is why I suggest something more deeply rooted.
I am not sure what to suggest to make it easy for you two, other than attempting to find out 'why' :/.