After 8 years of living together, my fiancé met another woman, now he wants us to move out of his house, do I have any rights

Are the children his? If so, you have a right to child support.

Otherwise it's his house and he can evict you if that's what he wants to do.

No, as an unmarried person you have no rights - unless you're in a common law marriage State.

What state do you live in? Are the children his? If they are not his then he can evict you because it is his house you aren't married to him. If the kids are his then he can still evict you but he would also owe you child support.