MIL died over a year ago. At the time, I didn't cry and just focussed on supporting DH who was very upset. I just assumed that grieving would ultimately kick in, as MIL was in my life for nearly 40 years.
However, I find that instead of grieving, what I actually feel is relief that I no longer have to deal with her. I managed to maintain harmonious relations with her for the 40 years. However, the constant lying and manipulative behaviour and favouritism to certain grandchildren was challenging. I feel really bad that I can't draw a line under it and focus on MIL's good qualities.(of which there were many).
I could never admit these feelings to DH. He misses her but acknowledges that she was difficult.