Sorry to hear about that. When I tore my event jacket about a year and a half ago I used a goretex patch. It is still firmly attached to the coat after lots of use and probably about three or four washes (I only wash my gear by hand, so don't know how it would have coped with a machine wash, although I would imagine it would be fine). I have never noticed any water getting in.
There may be better options as this is the only option that I have tried but it has done what I hoped it would do.