Is this an obsession

As most of you probably know I am having chemo, I have been told that my immune system is reduced and should take precautions to avoid catching illnesses such as colds.

My elderly mother has had cold for the last week and so has DGD, however I have to look after DGD so I have been really careful, not kissing her etc and washing hands. I banned DM from the house last week until her cold was over and today thinking she would be ok, I asked her to come over to see DGD, she came and was not better, she was gasping with her copd and coughing lots, she refused to eat and is not good, however this is not my responsibility. She went out yesterday and never stays in, I am angry because she should have said she wasn't well yet and stayed at home. She refuses to see the doctor.

I am so scared of catching anything, I feel my home is now contaminated, I am breathing her germs all the time. I have been like this most of my life but Im worse now due to my immune system. I just don't know how to avoid illness, I really would lock myself in a bubble if I could, I handwash lots of times in between removing food from the fridge and eating it. I don't know how long to leave the sofa before I can sit on it again after DM has sat on it. Also My friend is a care worker and sometimes she smells of urine (probably from dirty people houses), my sofa sometimes smells after shes gone.

I hate going into shops where I can hear others coughing etc. If I see an old man spitting I will remark that he is a dirty b......d. My hands are sore from handwashing but I just don't know how often to clean things and I think my mother is just being really vindictive its like she s saying her germs are ok. Any advice, I really cant help being like this.