Obviously, you didn't go into to much detail about your mom other than she is controlling.  Without knowing the facts that is a matter of opinion.  I think you should be ashamed of yourself for not letting your mother see the kids unless she was in some way abusive to them.  Who cares if she does not get along or like your husband.  She is still their grandmother and you as her daughter should ensure that they have a relationship with them. 

My sister in law is my "monster-in-law"!!  It doesn't matter what is going on she can never be happy for my husband and I.  Just to give you a few ideas, the night before our wedding she cussed us both at our wedding rehearsal for not wanting to go eat at the restaurant with her.  I'm sorry we had a few more important things on our mind!!

His parents invited us to go on a short weekend trip only a few hours away.  All was going well and about midnight someone was knocking on the front door.  It was her and her soon to be husband, she cussed us all out for not inviting them.  Even though his parents had been on several trips with her to other locations.  She stayed the rest of the trip and was miserable the whole time because she hates hiking and the mountains, maybe thats why she wasn't invited in the first place?

We share the same dog groomer and one day my husband asked her to pick up our dogs.  Well for some reason our dogs got hairbows in their hair while her dog did not.  She ripped their hair bows out and threw them away saying she thought we wouldn't want them to have them?!?

When we announced we were pregnant with our first child she cried and screamed and was mad at my mother in law saying she shouldn't be happy for us because she wanted to have a baby first.  Everyone else was happy but she screamed at us all. 

My husband has always been so supportive of his sister and never wants to let her down.  He never really says anything to her when she throws a fit or starts another tantrum.  She is just insane, i've never met anyone like her.  I have plenty more stories to tell!