Do I forgive her? UPDATED

So, long story short...my husband lied to me and went to Europe. He said he was visiting his mom and brother in Florida, but went to Europe with his brother instead.

We are working through that currently, so I don’t need advice on it, but thank you.

However, I am also upset with his mom. When I found out he might be in Europe, I called his mom. I had been texting her all week, and she had been short with me. My husband left his phone at home, so I could only contact him through his brother and his mom (so I thought). So, I called her and asked if he had been there all week. She said yes, and that they were on their way home in the truck. This was a blatant lie, as they were still in Denmark.

I was so upset that a grown woman would lie and cover for her children like that. Obviously my husband made a terrible decision, and not only did she not tell him that, she played a part! I told her that my daughter and I did not need to hear from her anymore. She told me to watch what I threaten her with and that I was out of control.

My husband says I need to be the bigger person and make things right with her so that there isn’t tension. He says she will never apologize, so I will need to. My MIL is morally corrupt and incredibly selfish. I hate that everyone else always has to be the bigger person around her.

Do I just forgive her and keep her at a distance? Do I apologize without an apology in return? What would you do?

Update: I decided to bite the bullet and be the bigger person (again)

Me: I am sorry I threatened you with Autumn, I shouldn't have used her as a pawn just because I was upset. I was deeply hurt by the role you played in the situation, but I just want to move forward and mend things. It is important to me that we be on good terms and that you have a positive relationship with Autumn.

Her: Thank you .....Autumn and family are important to me...

It took everything in me not to rebuttals, but I just didn’t say anything further. Sigh.