i think it is especially hard for the surviving parent to cope with this tremendous loss. while we as the kids keep on living our lives and grow, your mom now lost that life-long partner and im sure shes having a really tough time grieving.
why do you think she doesnt want to spend time with you or your siblings? maybe seeing you guys reminds her too much of your dad. perhaps she hasnt come to terms that it’s real yet. have you had a talk with her about how you feel? it’s possible she doesn’t even realize she’s acting this way.
im sure she will come around – remember that all people cope differently!