Five years ago, my husband had an affair with a married co-worker that lasted two years.
After I discovered this, I insisted he stop the affair and quit his job. He did both. A month later, he left our home after an argument and again took up with this woman.
After four days he called me and we agreed he'd return and we'd work on our marriage.
However, he's become moody, and emotionally distant. He's told me he's not physically attracted to me and unable to show me any affection.
After 38 years of marriage I still love him and have forgiven him for the affair; but I feel lonely and downhearted. My self-esteem is gone. I don't want a divorce, but I can't see living in this pain for the rest of my life. I just needed to tell someone.                                                      

- Still Hurting

You need to tell someone else, too - a therapist whom you should see to work on re-building your self-esteem.
You've put up with his cold, demeaning attitude long enough - he's punishing you for the end of an affair, and for his own weakness in returning without honest intent. It seems the man you loved is no longer there.
However, on the possibility that his moodiness is also related to some medical changes and/or depression, I recommend you get him to see his doctor for a checkup and possible treatment. If you find he's perfectly healthy, start thinking about your own mental health and why you want to stay with someone who continues to hurt you so much.

I'm a single, gay man with HIV, Interstitial Lung Disease, and on oxygen 24-7.
For four years, I've been friendly with a woman neighbour who yells a lot at her family, and at me.
Recently, while out together after I'd been very sick, I was suddenly short of breath, as she kept asking questions. I kept gasping "Hold on!" She finally exploded, screaming hysterically that I "yelled" at her. I explained that I'd been getting frantic because I couldn't breathe. She raged on that she "couldn't take it anymore."
We had keys to each others' cars, for emergency use; she had a key to my house. I returned her key, and asked for mine back. She was also my Medical Power Of Attorney person, since I have no close family.
I've retracted the POA, and am getting a Living Will instead.
She still wants to be friends, and I've said it's up to her, but I won't "apologize.'

- Breathless in South Carolina

Re-define the friendship. She likely felt fear and panicky herself as she saw you struggling, and so she overreacted in the way she usually does.
You'd placed a lot of responsibility on her for your well-being, and this was a moment of truth which revealed it may be more than she's able to handle, when you're in a health crisis.
Four years is not a long friendship, to have become so binding in such a personal, responsible way. She obviously meant well at the start, but your being sicker lately may've had her anxious even before you set out.
Be open and realistic with each other, about what she can handle and how this friendship can best continue.
Perhaps if she knew to call for help when you have a similar episode, and also is aware of your other arrangements should your health fail, you can enjoy her companionship without the added component of dependency on her.

My sister is constantly trying to improve my life by buying or lending me self-help and lifestyle books.
Is there a book I can buy for her, on butting out of people's lives?

- Overstocked

Speak up. Thank your sister for her interest, but tell her that her not-so-subtle criticism has gone beyond annoying.
While she may think she's trying to be helpful to you, her Sister So-Superior tactics are easy to read as overbearing and judgmental. A close, caring sibling can be a great guide, but only if the approach to advice is supportive and encouraging.
If you're happy with your own lifestyle choices, tell her so.
But if you want to make changes, show her that you're a grown-up who can find your own good resources. To that end, scan the book shelves, look into helping agencies and/or consider counselling as the means to find new direction.