You do not need this highly toxic woman in your life, she will cause trouble. From your description of MIL she sounds NPD (a narcissist)
She has treated you very badly and tried to break up your marraige, you owe her nothing.
She sounds like my ex MIL a 100% b##ch. The woman never had a good word to say about me. And she wound my ex 'husband' (who was a mummies boy anyway) up against me, every time he came back from a visit to her he would be temperamental, sulky, hostile, angry.

Might be helpful to read this
Narcissistic Mother-in-Law Breaks Up Marriages | The Narcissist In Your Life

As for your husband, his first loyalies must be to you and your baby, to his own precious new family not to a person who has been hostile and nasty. You must come before his mother & her cronies every time.

Get as far away as you can from this toxic woman A.S.A.P!!