Hi Hiding, your solicitor sounds excellent and really on the ball. What a relief to have someone competent and skilled fighting your corner!
I'm so glad that your cousin has been with you to take the pressure off and field the calls from your ILs. I know what you mean though - it's also nice to get back to normal with the DCs and re-establish a routine.
I agree totally with PerfectStorm about the reasons why your ex isn't interested in contact with your DD. He has nothing to gain 'politically' and would expect her to hold him to account for his actions.
for your DD but for the best - she really doesn't need someone like him in her life!
I feel sorry for your ILs in terms of the pain they must be feeling, but your MIL's behaviour is totally insensitive and grossly inappropriate. She cannot be allowed to keep on ringing you or your family members like this.
It's good that you're intending to ignore her, but she sounds very thick-skinned and determined to try and influence things. Can you get the police to contact her and tell her to cease contact? That would probably give her a scare and shock her into leaving you alone. Are you keeping a log of how often she calls? She is harrassing you at a time when you need to recover from a serious assault and all the emotional trauma that has brought too - completely unacceptable and she's demonstrating that she doesn't care about your welfare (or that of your DD); only that of her son. If not the police, then I would get a solicitor's letter sent to her asap. If your ex is as disturbed and desperate as MIL is implying, who in their right minds would think it appropriate that he have (un or inadequately supervised) contact with the children of the ex partner he recently threatened to kill?! 
I feel strongly that when partners split up, they should put the needs of their children before their animosity towards each other, and keep things as amicable (and away from solicitors, courts etc) as possible between partners and extended family. But your ex came into your and his DC's home, attacked and assaulted you and threatened to kill you!
He does not deserve any compassion and understanding from you - he has forfeited that. He doesn't deserve that you ever waste another thought on him, ever!
He doesn't deserve to see his children at the moment - he has violated their mother and their home. 
I can just about stretch my compassion to his parents sympathising with him - he is their son after all - but their behaviour since this happened has been reprehensible. If they cared about you and the DC's welfare then they would not be enabling and defending him the way they have. 
Phew! It makes me so
on your behalf! 
Anyway, thinking of you and how brave and strong you have been throughout this. Don't let the bastards grind you down! 
Hope it goes ok at the fracture clinic.