Am I in the wrong? or over reacting?

hello me and my boyfriend have been dating for seven months, were pretty serious and have talked about marriage down the road, well recently he Re injured his knee (tore his mcl and acl) and tomorrow morning finds out if he needs surgery or not. I being the supportive girlfriend was all prepared to go with him to be supportive. untilled he informed me he asked his friend to go with him, and wouldn't give me a reason why he doesn't want me to go. I'm extremely hurt and upset by this. am I in the wrong for being hurt and upset? or as girlfriend should I be the one going to support him?