The green monster called jealousy...

I've been TTC for 4 months now. Right from the start I've been tracking my ovulation and have done everything by the book. Now I've found out that my younger sister is 8 weeks pregnant. She was off the pill for 1 month and had sex once and fell pregnant. When I found out I cried all night, I have never felt so utter and total jealousy in my life. It's now been 2 weeks since I found out and I'm really struggling to focus on anything else. I truly want to be happy for my sister but I'm finding it extremly hard. Is this extreme jealousy normal and is there any tips that you have to help me focus my energy on something else??