Is it permissible for a married man to enter into a Misyar marriage with a Christian woman without his wife's knowledge, and what is the ruling on masturbation in this case, and is that considered a betrayal of the wife, and is it permissible to stipulate non-procreation in a Misyar marriage?

1. Masturbation is forbidden and should only be resorted to in cases of dire necessity, such as fear of committing adultery. The situation you described does not justify masturbation.

2. You must marry a second wife if the first one does not fulfill your need for chastity. The first wife's knowledge is not a condition, and this is not considered betrayal.

3. Misyar marriage is valid, provided its legal conditions and pillars are met, whether with a Muslim woman or a chaste woman of the People of the Book.

4. A temporary agreement not to procreate is permissible with the wife's consent and through lawful means, with the caveat that using a method that definitively prevents procreation is forbidden because it severs offspring.