Interferring in law?

My mother inlaw is an interferring busybody. She has destroyed every important occasion for my family. Namegivings,birthdays,xmas etc. She has badmouthed me and my family even saying im a bad mother. I alone raised 2 boys who are now 18 and 21 and lovely young men. I have never even heard her say anything nice about her son. Now after no contact for 15 mths she wants to see my little ones aged 4 and 5. This i feel uncomfortable with as i think its wrong for the kiddies to hear bad things about their parents that arent true. I know children should have grandparents in their lives but what about if they are negative role models. We have forgiven her on many occasions but then something happens that she doesnt like she goes off again. We cant even have a wine on birthdays or xmas. By the way i have a great relationship with the mother of my big boys and she has always respected the choices i made. What would others do?