ever feel like someone's getting everything you should of had

we've been trying for a baby for god knows how long now, we got engaged in Nov before we lost our little miracle at 12 weeks. but this girl, as soon as she found out we were pregnant, she was trying. a week and half after we lost our baby she sent us a picture of her positive pregnancy test, not long after, she lost it and acted like it was funny. the other day she told us that she went to the doctors and they said she might be 3 months pregnant. We were sent another picture of her positive test. which made me so fucking mad. and now my fiance is helping her boyfriend propose. is it me or she actually tryna live my life and not even habe to go through the suffering I do. i wanna be happy for her but I just can't and that makes me feel even worse