I understand it's hard. My friend told me she was pregnant (well actually I guessed which in a way was good as I had suspected and prepared myself - she doesn't know about my pregnancy/ m/c). Anyway they have been trying for two years so I felt exactly like you - I was very happy for her and how I have been wanting this for her desperately for ages.... but......just not right now. I could never say that to anyone IRL because I feel selfish - and i AM happy for them, it's just that she's due 6 weeks after my EDD so it is going to be a little hard.
PS. I think it is also the timing for you because it is exactly how it happened for me. I got af and got really miserable that I didn't get pregnant, and then the next day was when my friend officially told me she was pregnant so I think I was already feeling rubbish. This week I am feeling better about it all so I hope that happens for you too.