Joy in shul, but not in my heart

Today there was a Bar Mitzvah in shul.  It was Rosh Chodesh Adar (the new Hebrew month).  Adar is considered a joyous month.  The saying goes that when Adar enters, joy increases.  The Bar Mitzvah boy had his first Aliyah (being called to the Torah).  There was joyous celebration, dancing and throwing candy.  This added about a half hour to the prayer service, which in all lasted almost two hours.  I wasn't in to it.  When I go to shul these days, all I want to do is pray and say kaddish.  I don't feel I can participate in other people's joy.  I don't want to be captive to other people's needs.  (But I feel I have no choice but to stay to the end of services when the kaddishes are recited.)  If I'm being selfish, so be it.