mom's awful 71 years old dinner

"Better a dry crust with peace and quiet than a house full of feasting, with strife.”
Prov 17:1

Apart from my wedding, we never have any celebration feast at my own family. Last Sunday I have organized a surprised dinner for my mom’s 71’ birthday. I thought it would make my mom feel happy. However, my elder brother and sisters (they are my step brother and sisters, my mom married to my dad after their mom passed away) did not feel happy about my arrangement. They did not tell me honestly, when I asked them to come for the dinner. By the time, they showed up at the dinner, they were obviously unhappy about having this feast. The reason is that after my dad passed away, they do not feel obligated to treat my mom as their mom anymore. It is so sad to see them not be able to treat us as a family and want to use their way to identify themselves as outsiders. The next day Mom called me and told me that she did not feel hurt any more because she is able to forgive them. However, she still cannot have a sound sleep that night because she felt so bad for them. I pray to God for mercy and I know I need your prayer too.