If you need motivation to practice your Aikido, then practice in honor of your mother.
My Grandmother passed away a few years ago. It took me awhile to get over all of the grief and depression of her death. I eventually learn to simply remember the good times that I had with my Grandmother and the wisdom that she had taught me. Occasionally, I remember her and start to cry because I missed her, but that is normal.
Please understand that all of the feelings that you are going through is completely normal.
Just remember: death is the ultimate enemy. And no matter how much we might try to escape it, it will still haunt us.
If you have any feelings, emotions, thoughts that will lead to negative actions (suicidal thoughts, cutting, drinking excessively, old habits, etc.), don't be afraid to ask for help. Okay. I speak form experience.
May God comfort you and be your shelter and grace.