Sorry about the loss of your father.
In similar situations I usually sink into depression, but I have experienced anxiety as well. When we started making arrangements after my grandmother died I actually fled the building. It was when we were putting together her obituary, for some reason listening to her life get summed up, itemized and listed really stressed me out badly. I don't have any tips that would help, everything I tried (even medication) failed me then. I just had to get through it and it was a very difficult year. Good luck to you.