Double Standards in Marriage Debate

I (F) have been in a long term relationship with my now fiance (F) and will be getting married

later this year. We are keeping it small so that it's cheaper and to make it a more intimate

event. My sister is extremely catholic and has been anti lgbt since before I came out.

I have decided not to invite her since she doesn't believe our marriage will be a real marriage.

For context, she's married and although she always wanted kids, she had to get a

hysterectomy for medical reasons. One of her religious arguments for being against lgbt and

gay marriages is that they cannot produce life. She thinks marriage is between a man

and a women who can be joined in sex only when there is no contraception and their sex act