mixed emmotions

Just thought I'd post, found out today that my sister-in-law is pregnant with her 2nd child. me and my husband have been trying for 9 months with not even a sniff of the slightest BFP. I feel so mixed on one hand I'm so happy for her I mean that's my little nephew or neice in there but then on the other hand inside I'm gutted it's not me. does anyone ever feel like this, I feel so bad that I'm not 100% happy for them. xx