Lost my best friend

A little over 6 months ago I lost my bestfriend of 10+ years. We drifted and no longer spoke due to situations happening. Yesterday was her birthday and I made that effort to send over some goodies even though we haven’t spoke. I miss her terribly and think about her everyday. I received a message to thank me for the gifts but I have not yet opened as I honestly don’t know how to reply. I truly do miss her but I have no idea what I could possibly say to her. I love her more than anything still and it causes me pain as I have not found a friend as good as her. Can I have some advice on maybe what to say? She basically just asked if I am well but I do not want it to be a conversation that lasts a few seconds and again we do not speak ever?