Hugs to both of you, and know that our prayers continue.
I can relate to the mixed feelings. On one hand, you're glad he was released from the hospital. Yet on the other, there's the apprehension and the feeling you're both on your own now. I remember when PizzaBoy came home after having his leg surgery two years ago, I had those same thoughts. While in the hospital, it took him longer than average to awaken from the anesthesia, and he continued to have some side effects for several days. I was pretty scared, and actually slept on the floor in his room for the first few nights after arriving home. Even after I moved back into our bedroom, I was still awakened by any noise, thinking it was him.
Mariposa gives excellent advice. We used a medication chart, also created in Excel -- not just to keep track of dosages, but I was also terrified that given my state of mind that I might forget whether he'd had his medications. Also, keeping track of the time was necessary as the pain relievers could not be given within a few hours of each other.
Keep us posted as you are able. Yet, also be sure to take care of yourself.