Sister issues

Ok so may be a little bit of a rant so here it goes .. 
So my bf and I (21 and 26.. 4 years together have a house together etc... Went to look at engagement rings . We told two close friends we were going looking . Somehow or another my sister got told , who then told our parents (bf was going to ask my dad) so instead of being a surprise to them it's completely ruined. She is 24, with her fiancé (32) living in my parents house trying to conceive , she got engaged in June. She is now getting mad because I'm gettin engaged in the same year as her well as she is asking if I'm ready to spend my life with him (because him and I had issues due to stress after both his parents passed away. I stayed at my parents for a few days to give him some space)  etc saying maybe I shouldn't . I love this man with everything I got , he's the only one I see myself having a family with and moving forward , our relationship is better then it ever has been . 
Is it jusitifiable to not want her to be a part of my wedding party or anything like that? (I am one of hers)
As well as am I really mean for wanting to get pregnant before her just to spite her for acting like this towards me and not being supportive of her only sister? (She's been trying for 2 years)