Hi Marlene.................
I am so sorry about you mother. I lost mine 7 years ago.
Don't be afraid to let your feelings go......... it will help. You will never in your lifetime ever lose those memories of your mother. The last time I saw my biological father was when I was 17............... I am now in my early 50's, and I still remember him ......... I still have the memories of when I was 4 and 5 years old of him........ So don't think for a minute you will lose the momories of your mother if you let your emotions go.
Maybe you should talk to your sister or another family member you trust about your mother and how you feel. Feelings happen inside of everyone and you can't carry the woes of the world on your shoulders forever. If this doesn't help, then I suggest a professional counselor.
Don't let that black hole eat away at you. You have your whole life ahead of you with lots of new adventures.