Q. A few years ago, my husband of 15 years started an affair with a girl half his age who lived with her husband and child a few houses from ours. They lied about it for months.

Well, the girl broke it off and moved away. Then my husband made a promise to make me happy again and work on our marriage. During this time, my best friend needed to leave her abusive husband. My husband and I loaned her money, and she moved in three doors down. Guess what happened next? I saw 250 text messages back and forth proving it. It was like history was repeating, but it felt much worse. This was my best friend, and she knew the pain I’d been through. I moved out and, two years later, do not regret that decision. My question is: How do you deal with betrayal from people who are supposed to love and protect you? I’m not sure that I can trust anyone.

A. For reasons I have never understood, “the best friend” is often the interloper. Just as they say blood is thicker than water, for some people sexual attraction must be stronger than friendship. Think of it as people being conscience-free. Dealing with betrayal is hard. You just have to know in your gut that some people are skunks, but by no means everyone. There are no warranties, alas, about fidelity and loyalty. If you’re obsessing about these past events, try letting a therapist help you put the hurt and anger to rest.

Q. I am 45, female, with two siblings. My younger brother, “Joe,” is 41 and married with four children. Six years ago, my husband committed suicide in our home. Joe and his family welcomed me into their home for many months following the death.

In early 2009, Joe lost his job and asked to borrow money. I was happy to help. He found another job soon after, but for less money, and he continued borrowing. His tearful calls asking for money were always accompanied by the request that I not tell his wife. Fast-forward to September 2010. I told him I could no longer give him money, having no more to give. Of course, this realization came $18,000 too late. Talking with my mother, sister, and Joe’s wife, I realized he was on drugs. While I was giving him money and hiding it from his wife, I was enabling him.

My question is: What do I do? The family cannot pay for rehab. Obviously, my brother needs help, and I think it will have to be inpatient.

A. The family should have an intervention. Tell Joe of your fears, and if he wishes to get straight, the family should look for city or state agencies that can provide treatment. Should he resist, family members should go to Nar-Anon so that his addiction will not wreck everyone else’s life.