I love someone else more than I love my husband
Are you comparing her to your husband?
I'm comparing the joy I have with her versus the joy I have with my husband.
If you find yourself loving someone other than your husband, it isn't fair to him since it's expected that one's spouse will remain faithful in marriage. You should first work on your relationship with your husband and see if it is still possible to rekindle the love that you once had for him. If you can't, then you should break up with your husband so that he will be free to find someone who will actually love him.
I don't think I should sacrifice my life to him.
No one is saying you need to sacrifice your life, just that its unfair that your husband sacrifice himself for your happiness when you love someone else more. Don't you want him to be happy and find someone who loves him too?