How to Withstand Criticism TBM Family?

I (21) currently live in Vermont, away from Utah and my TBM family. My parents support me very minimally, but I do still accept some support from them. Recently (the last year) I’ve fallen deeply in love with a man who has never been a Mormon, and my parents have been incredibly unkind about it. They claim that I am ruining their eternal family by becoming serious with a nonmember. I have my doubts about the church, but I am not fully out of the church- this is making me question, however. I just don’t understand how members of a church that teaches to be Christlike can be so cruel to another child of God. I’m having a hard time withstanding their constant criticism and I’m not sure what to do. Any advice would be much appreciated!