My mum

I'm feeling more than a bit conflicted. I was very close with my mum, loved her so much. My dad died very suddenly when he was in his mid 50s my mum adored him, never ever got over him. She became very bitter and as her only child I became I suppose her everything. But this is where my problem lies, she became very hard to be around, different problems occurred and she made my life miserable. I never let her down I was always there for her
So why can't I remember the happy times with her all that's in my mind is the stress of her final years