No, YANBU to be upset on having been deleted by a friend but, as others have said, it would be unreasonable to expect everyone to react in the same way as you feel you would do if the circumstances were reversed.
In a period of 18 months, preceded by 18 months of not being able to conceive, I had numerous miscarriages and a ruptured ectopic. I struggled enormously when it came to being around people whose pregnancies/babies were at the same stage as any of mine 'should' have been. Even harder was being emailed by my SIL, immediately after I'd just had life-saving surgery to resolve the ectopic, to be told that she was expecting a baby with the same EDD as my ectopic :(. At that point I really didn't need to know that, I needed to recover from the surgery, the loss and the dodgy hormones floating around my body.
Thing is, she thought she was doing the right thing because that's what she would have wanted. She didn't know that I'd been told I'd be unlikely to carry another pregnancy to term - why would she? I hadn't processed that myself. Meanwhile, local friends were brilliant at just being there for me; emails, texts, phonecalls and, most importantly, being very upfront about the whole thing and asking if I'd like to talk about my failed pregnancies rather than avoiding talk of babies. When a couple of them got pregnant they rang so I heard it direct and had a chance to opt out of being around them if that's what I needed to do - I didn't. However I was able to explain that whilst I was desperately jealous of their pregnancies I was also thrilled and wanted to celebrate with them as I knew I didn't want to live under the black cloud of doom for evermore.
My feeling about your situation would be to encourage you not to feel guilty about your pregnancy but recognise that your hormonal state may be influencing your reaction to being deleted on FB. Your friend may appreciate a phone call, may prefer a note or an e-mail, something that is more personal than FB and takes more effort. She may not. She is your friend and friendship is about more than FB. Let her know you care and that you'd like to do the right thing by her pregnancy-wise.... it may well be that she wants people to be open about their own pregnancies but, as the pregnant person, it's you who is in the position to do that.
Good luck with your friendship and with your pregnancy.