Sister in law has distanced herself from us during a time of family illness

My husband saw little of his elderly half sister and her husband until we moved back to his home town. The half sister is his only living relation. Following the move, they seeemed happy to meet up socially every few months though they only live 100 yards down the road. They have always called the shots with these visits. When they were ill I have always offered help, though they have consistently refused this, even though they have no other family nearby.
Now my husband is ill, following a stroke, and they have offered no practical help whatsoever, though I have no family nearby. His sister has pestered me with texts however, sometimes 3 a day! A month is due to elapse following the sister's first visit when my husband came out of hospital, and her second proposed visit. She has really messed us about with cancelled visits too. Why couldn't she just phone up and pop round for half an hour? It has been very busy for us, with the rehab team and my part-time job. The husband of my (half) sister in law is a sarcastic control freak and the two of them have made me angry and upset my husband too. We are seriously thinking of having nothing more to do with them.