Is it the hormones?

Rachael • I'm a 34 year old RN and mother of three (soon to be four). Kinda feel like a 1st time mom, since my youngest is 12!
So I had this friend. She's the one who introduced me to my boyfriend five years ago. She and I were very close for a long time. Two years ago I broke up with my boyfriend, but she and I remained close. I moved out of state, but she and I still talked pretty regularly, I always saw her when I came home to visit, etc. my boyfriend and I remained friends, no hard feeling after the breakup, etc. well, about a year ago, I decided that I made a huge mistake breaking up with my boyfriend. At that time, he was dating another one of her friends. Nothing hugely serious, they went on like four or five dates. I waited patiently, I thought it would be selfish to make a move if he was happy oth someone else. But he wasn't. He broke it off with her. A few weeks after that, he and I went to a wedding together (out of state), and I made my move. We have been happily back together since then, and are expecting a baby September 15. We couldn't be happier. 
Here is the problem. The girl he dated hates me. With a fiery passion. Blames me entirely for him not wanting to be with her. Kinda seems like she thinks that if I hadn't come back, they would still be happily dating. They wouldn't. He complained about her every time he went out with her. While he may not be dating me if I hadn't moved back, he certainly wouldn't be dating her. 
She is very close friends with the girl that was my friend. Over the last eight months, my friend has consistently been too busy to hang out with me, except twice. When she does, she is secretive and doesn't want the other girl to know. To the extent that I had to pick her up and drop her off at locations that were not her home, so that the other girl (who also was her room mate) wouldn't know. Wtf? Are we 16? She (my friend) got very catty with me one day on Facebook (very publicly) but then texted me right away to say she just had a bad day. I unfriended her about a week after that because I felt like the cattiness wasn't due to a bad day, it was due to her wanting her friend to see her be shitty to me. It took her over a month to even realize I unfriended her. At this point I just don't want to be friends anymore. I feel like I'm constantly living in this "second class friend" situation. Am i taking things too personally?