Having quit one of the bands a couple of months ago here is how it went.
I had decided to leave as the relationship between myself and guitarist, (HIS band!!!!), had deteriorated so that we were hardly talking. I decided to tell the band after 1 particular Gig, (out of respect for my other half who sold it), and also there was a 3 week break due to holidays etc . We were using a Dep drummer that night but I told our regular Drummer beforehand as I have the greatest of respect for him and we got on really well.
When I came to make my announcement the bloody guitarist pre-empted my announcement in the car park when we were loading by saying, "Stuart, I think we need to talk". My reply, "Well actually A..., I have decided to leave the band so not sure there is any point."
I said I would not drop them in it and would play any Gigs they wanted and help find a replacement.
Not heard a word since, (which suited me), other than from irate venue owners who haven't had their usual courtesy call before the Gig and "Where are the Posters!"