A WISE CHOICE ........
To grieve in some manner and in some timeframe .... is a wise choice!
Please do NOT do what my Mother did during her life. She lost her husband of over 40-years, my Stepfather, 19-years ago next month. Until her death bed on January 14th of this year, she never would accept his loss.
She never did accept - but instead, for 19-years, often re-lived his years here. Some of that was her dementia. Some of it was her well-practiced system of denial.
Whether it's with a counselor, your older sister or a support group - DO continue to grieve. If it's possible, all three sources would be wonderful. You might gain quite different perspectives that way.
I too, experienced losing 4 (of the 5) adults closest to me - and my dog of 12-years - during a 3-year timeframe - 16 to 19-years ago. It was a few years after my divorce ... and I did get involved with a psychologist for the first time in my life, as well as, a support group.
You are not alone - as at least one other person said here.
Peace and wellness
Rob & Gizmo