I'd take a cue from your signature and accept his apology and just answer, "Yes," (be queen of the one-word answers :-) and go discuss the whole emotions-everywhere thing tomorrow.

You told him what you were wanted and were going to do and he responded, as in, "Okay, got it, see you Monday, that's good, I agree." That he apologized for not being able to take the time to respond more fully the first time and expressed his sorrow if you took that the wrong way and still wants to see you tomorrow; I'd accept that and go from there.

It kind of reminds me of the Progresso soup commercial?