Feeling like a failure.

My husband and I have been TTC for over 4 years now. I will admit that the first year of TTC I would cry everything month my period came. It was an emotional roller coaster. But I finally became numb to the process and haven't shed a single tear over not conceiving for almost 3 years now. Well... That was until today. Today my husbands ex, mother of my step daughter, announced she was pregnant. Her and her husband have only been married for 3 months. 
I know it seems petty but let me first say that I love my daughters mother. Her and I get along great!! But I can't help but feel like a failure to my husband. I can't help but imagine how much happier he would be if he stayed with her. I feel like my husband made a mistake marrying me. I feel like a broken toy. That I am no use because I can't get pregnant. I hate this feeling so much 😭