I feel for you. It is very very hard when you are struggling and others around you seem to be getting pregnant all the time.
YANBU to feel angry and upset. That is natural. Go over to Conception where there are lots of threads with people in the same boat supporting each other.
YABU to vent your feelings to a newly pregnant woman though. Asking for trouble.
To put things right, I suggest you phone her up (don't email) if you can't see her in person. Explain that you are of course very happy for them both (even if you don't feel that way right now) and can't wait to meet their lovely new baby. However, you have been trying for a while without luck, so although you are very happy for them, it is hard for you to talk about pregnancy and babies at the moment. And then apologise again for upsetting her.
Have you only being trying for 7 months, or is that 7 months of charting etc after a long period of more relaxed trying?
I am not one who thinks relax and it will happen, but unless you have been trying for a long long time, I think you need to take a different approach as clearly you have become very stressed.
If you have only been trying for 7 months, that is quite average really. Ditch the charts and just have sex three times a week with a healthy (not strict) diet and lifestyle. A very strict diet and analysing charts might be making you feel worse when there is nothing wrong with you. Perhaps if you like the scientific approach, get a Clearblue Fertility Monitor instead of the charts.
If you have been trying for longer than a year, then see your doctor for a referral to a specialist. But less than a year is totally normal.
I do understand that it is very hard when you want to be pregnant but you aren't. I've been there. But other people will get pregnant and you need to find a way to smile, say congratulations, and then deal with your emotions privately with your partner.