I think all you can do is to support your Mum, no one knows the pain and trauma of separating from a loved one until it happens to them, the depth of pain is like nothing else.
I've just separated and the pain is raw however my pain has been going on for 2 years, that's how long it took us to seperate, why so long? because I loved her and was patient to her affairs.
This is the meaning of love, its nothing to do with sex:
Love is the stubborn mental attachment to someone that survives all ills, is tolerant, learning, and willing to change to keep a relationship alive.
I'm affraid that I won't get over my partner, God I hope that I can move on.
The pain can be so intense and deep.
Support you mum, she needs it, don't question her attitude,
Give her a big hug everytime she is down