You can't make him do anything, and yes, while it may be useful to keep the peace but your mum has made it clear that she doesn't like him so it may be useful to remember that. Please do not hold it against him - I know you resented him for the whole thing when in reality, your mum is at fault too - if not more so. She could've still had a relationship with you, while refusing to see your husband. The issue with his children is point scoring - it was your choice to take him on with kids etc, and do what you do for them just as it's his choice not to go to your mums, even though it seems unfair.

Can you not go alone if it means so much to you? Perhaps your husband will wait in the car around the block or something for you? Although he doesn't support you in going to meet your mum, perhaps he can be a support for you afterwards, esp if you do not hear what you want to hear from you mum.

Good luck.....