Husband taking a Christian as a second wife and ill-treating the first wife

Q:

1. My husband married a Christiam girl who didn't convert to Islam. Is the nikaah valid?

2. He stays 1 night only with us and its affecting my children now. Is this permissible? He treats me, as a first wife, very badly. He talks rudely to me and is always angry with me. His 2nd family is always treated well.

Keeping a gift from a non-mahram boy

Q: I met a boy and we both had feelings for one another. We both did not want to date as there is a lot of sin in it. Our intention was and is to get married when the time is right and until then, whether our paths cross or not we decided to cut off contact until then. We have no contact at all. The only piece I have of him is a chain that he gave me, will it be sinful for me to wear it?