I really do know how you feel -- my dad died two years ago on May 4. I was barely back from his funeral half way across the country and with still no time by myself to grieve when a beloved cat, Calliope, died on June 4 after a short illness. I felt guilty about tears for a cat when I had just lost my father and hadn't yet had time to mourn for him. Coupled with the grief for the loss of each of them. Knocked me into a funk and a real sucky depressed week -- made worse because my birthday was 5 days later. Not a wonderful time at all.
Whatever you've held in your heart is never truly lost, but please accept my sympathy for the loss of your feline friend and your father.