Here’s the situation:

My fiancé has five kids in his family. His grandparents raised him and a couple of his siblings. So my fiancé considers his grandparents his parents. His mom hasn’t fully raised one child yet. She loses custody for one reason or another. Out of the five kids only 2 like her and that’s because the one has mental problems (in his late 20s) and the other is still under the age of 10 so neither one fully understand. His mom has been in the picture off and on but she never has or to this day still doesn’t act like a mother. She acts like she still in her early 20s and hooks up. She tries to act like more of a best friend to her kids instead of being a mother. She always cause dram for no reason in the family.

Example: she wasn’t around for about two weeks and there was less drama,fights and stress.

My fiancé and his older sister and one younger brother despises her.

My question is:

do we have to or should we invite her to our wedding?