You are fortunate to have the support of your husband as many caregivers have no immediate support. It's difficult to define the depression as grief and loss can bring it on... coupled with taking medication.... sometimes the medication dosage needs and adjustment and sometimes, it is necessary to switch to a new medication.
As for motivation, etc, I think that all of us as caregivers set goals for our loved ones as we cared for them, but neglected to continue setting them for ourselves.
Part of my lessons learned from caregiving for all those in my life was to begin living my own life more fully. I now had a choice.. no one was in charge of me... my choice was to reclaim my life.. setting some short term goals and some long term..the three I chose immediately to do within a month were to go to the theater more often, volunteer at a museum and to take up the art of pottery.ceramics which I did..
It has been almost 4 years since my mother passed... the last of the caregiving... and I find myself caregiving to myself.. to heal myself emotionally, spiritually, physcially and mentally.. it is full time work..but as a result, I am truly finding more love, peace and happiness in my life and I am truly grateful for the choices I am making.
I encourage all to find some hobby.. no matter how unmotivated we might be... something that makes your heart sing.. lets the little child inside out to play.. so that you can choose to begin living your life more fully as well.
richest blessings.. may your journey be gentle and nurturing.