Am i wrong in doing this?

Sit back cuz this is going to be long.

So me and girlfriend have been going out for three months now and these first few months we've really hit it off. Literally we became so close so quickly, she said to me at the beginning that when the time came, she would never say shed love me on her own, ID have to say it on myown first and then and she might consider saying it. One month later and she told me all on her own before I was even sure about it. But now I really do think that maybe one day we could get married. It is early yes but I guess it just happened. We spend loads of time together and her mum loves me. Now thats the back story.

It all started yesterday when we were in town to go to a gig. We went in early to get some food and do some xmas shopping. Now earlier this day, she wasn't acting the same so I asked her what was wrong but she wouldn't say anything so I asked her again. Her response again was again nothing so I started bugging her about it. 30 mins later she still hadn't given me anything and what she said was that she wasn't any good with emotional stuff. Which I understand cus shes moreover a guy in that sense. But I was saying that she could tell me anything and she was like I know. And I let it go cus she said that even her best friend doesn't know so I thought it clearly wasn't my place then. So we went to the gig, then on the train back I was thinking to myself and she kept asking what was wrong and I said nothing as there was nothing but then she went into a hissy fit with me saying that why wont I tell her and blah blah which was obviously very hypocritical. But I left it and got go her house and because her mum was there, we just got better automatically and I had forgotten all about it. So today came along and I didn't see her in school till about midday. I saw her sitting with my best friend who shes known just as long as me, he actually got us together. But I walked over and sat down. I looked at my friend and asked what they were talking about and he said thAt my girlfriends grandmas cancer had spread and she didn't have very long left. At that point all I thought was that she told my friend and not me. I looked at her with a look like WTF and she just looked at me and ignored me. So I stormed off.

I mean she told my friend rather than me. I thought we had this really deep connection and I really care for her so I would have provided emotional support. If it was her best friend she was telling I wouldn't have minded but the fact that she told my friend over me really angered me. She tells me things like she wished we lived together and joke about getting married now.

I'm just really hurt and I don't think she gets it :/ I mean what am I supposed to do? Is she being unfair or am I overreacting? Any help is appreciated, thankyou