OP, you sound like a nice person to have cared so much about your ex’s mother. But face it, she was your ex’s mother and not yours. It’s rare that a relationship with former in-laws lasts past the marriage or relationship with your ex. Your feelings do you credit, but she’s not your MIL anymore once you and your ex divorced… I understand somewhat. My mom has maintained a relationship with my ex primarily to keep in touch with her granddaughter and partly because Mom makes her decisions on the basis of who she likes and not necessarily who she’s still related to. That doesn’t bother me - that divorce was a long time ago. I can understand that if it hadn’t been so long since you divorced and if you had maintained an amicable relationship with your former MIL that you felt left out of the funeral and will. Divorce is usually final - It’s time to recognize that those relationships with your ex and their family are over and you need to look forward and not backwards.

He probably didn't want you to be too happy. An anagram of mother-in-law is "woman Hitler." Jus' sayin'.

you are the ex. Unless you have kids there is no reason for you to have contact.