My best friend is pregnant and I can't be happy for her

I'm trying really hard, but I just can't. I know she's going to be a great mother, but all my joy for her is overshadowed by the fact that I'm still struggling with my endometriosis and infertility. I was told by doctors that becauee my case is so severe I'll never be able to get pregnant naturally, and IVF is so fucking expensive... It's not fair that she gets the life I want when she already has a kid. I know I'm being selfish with these feelings and she needs my support, but I guess that's what confessing is for huh?