I need to keep my bitterness to myself

The only chance we may have of getting pregnant together is IVF with ICSI, that’s quite expensive. I keep seeing every one including people I know and don’t know pregnant, a lot w twins.. I’m happy for them but secretly wondering why it can’t be me.. I’ve been so depressed since finding out the news. I do have a beautiful seven yr old daughter but she isn’t biologically his. He’s such an amazing father to a child who isn’t his blood, makes me constantly wonder how he would be an amazing father to his own. Ugh...