WHY should I be happy for YOU???

I woke up in the middle of the night worrying about my brothers upcoming wedding. While I'm 

happy he's getting married again and is happy. I started worrying about their quick engagment and upcoming wedding. The wedding is June 13 and they probably got engaged about a month ago.  So, what was I worried about? I was worried they will spring up an "announcement" at the end of the reception. "Oh by the way we are expecting."  I was imagining my reaction which would be me walking out so I don't embarass the crap out of myself by crying or just throwing things. Heck I NEVER know how I'll react. Plus Tony(the one I cry to) won't be there and it'll make it sting worse. 

 This is a legitimate worry because it will be the first time I've met any of her family and they will from then on out see me as the bitch Sister in Law who walked out on her brother's wedding.  Now, as MUCH as I love my brother he's not the most sympathetic of humans (in all honesty my family is a little lacking in that department) and I can see him saying, "shes a grown up she'll get over it." So, I called my mom and my mom said "I hope she announces that." WHAT????  Since when was she OK with one of us being pregnant before we got married?? I then told her to get him to give me a heads up if she's pregnant because I want to know before hand so I don't make a fool of myself and I can prepare myself emotionally. 

I think others think I'm selfish, but I'm not at all.  In all honesty I'm thinking of them because I don't want to ruin it for them. My mom tells me to be happy for others who are pregnant and I use to be (when we were FIRST trying), but I can't be.  I finally said, "That's like telling a person who has cancer to be happy for all the healthy people." She laughs when I tell her I can't be happy and I won't be. Something I've learned is you can't tell people how to feel. It's difficult not to, but you can't. What they feel is what they feel. There are reasons behind it. 

So, WHY should I be happy for those who get what I want easily??  I'm not talking about money here.  In time I'd be O.K. with it I guess, but at first I'd be pretty upset. 

 While people say you can't compare your life to anyone else's in all honesty it's how I measure time.  Example: This couple has had 3 children(one starting Kinder) in the same time we've been trying for one" or "this couple has been able to afford IVF(or their amazing insurance covers it)  and got pregnant and are now on baby 2."  I know many who have, met, gotten married, had two kids in the time we've been trying for one. It's painful and this is why Infertility is a whole different world and they have to try and seperate themselves from the "Fertile world."  They can't POSSIBLY understand 100% what we're going through, and I don't need someone telling me to "be happy for someone else." It's been OUR turn for a long time it's not theirs.