Hello Camero,
You certainly have a lot going on within your family, & I can see how this all worries & upsets you.
If you can make a long appointment with your GP & talk over all these problems, they can give you good advice. All your family member may have their own GPs they can talk to.
Your GP can help you, &, if you want, they can help find a Psychologist to help you learn how to deal with the stress & upset, & how this is getting you dowm.
Your brother, your father & your wife all will have other specialist Doctors, who they have seen for their conditions. You might have to help to get in contact with some of these & have your brother, father & wife talk to their own Doctors.
Personally, I have had breast cancer, & surgery for that this year, & I know they have people who will be willing & able to talk to your wife about any changes in how she feels about sex.
Try to be patient with your wife. She has been through a lot, & it's scary & stressfu, & she too, surely feels for your brother & father, just as you do.
May I ask, how do you feel your relationship with your wife is going? Are you close & strong, like a team? Or is there so much stress that this is making your relationship & communication between you difficult?
Talk here as you feel comfortable to do. You don't need to even tell us the answers to my questions if you don't want to.
Warm regards,
mmMekitty