My cousins Controlling girlfriend (advice needed please comment)

My cousin's girlfriend/mother of his children is very controlling. She doesn't let him come places with us at all. He isnt allowed to invite his friends kids to their kids party. Once she kicked me out my little cousin party. She was upset about my girlfriend's attire. She had on jeans and tank top (small chestside) . She just wanted us gone. My girlfriend was upset because walked up and said take kid and leave thot. My cousin didnt say anything to her it hurt my feelings.

He good man takes great care of the kids and his girlfriend. He works hard. She will call job and demand he talks her just because she can. She threaten to take his kids away if he leaves.

Once he took kids to movies on Friday night. She came into theatre and snatched them claiming it was thier bed time. She tells him all time you won't have me looking stupid like my dad had my mom. Her dad left her mom when was a little girl. He has been with her trying stick out for over 7 years. She down right mean.

He been trying fix her daddy issues . I'm upset because my children ask see their little cousins and I always have lie. My little cousins /her own children tell her she mean to everyone and her reply is tell them shut their mouths. I just don't know what to do.