I'm jealous because my cousin and I aren't that close anymore?

My cousin and I used to be close, but now that she has a kid were not that close anymore. The thing is, she has become really close to her husband's cousin and his girlfriend (mostly his girlfriend). Now that my cousin has a kid she can relate to them more. I personally can't stand her husband's cousin and his girlfriend. The guy is a jerk and obnoxious. He goes around talking about sex all the time and he's so sleazy. Meanwhile his girlfriend smoked pot when she was pregnant and is disgustingly thin, she didn't even try to gain weight when she was pregnant, in fact I would say she tried to lose weight. I just feel so jealous of their friendship now, plus I feel like I've been replaced by people who so not better than me. She talks about them like they're so awesome, but the truth is they're just the only people she knows with kids around her own kid's age. Is it bad that I'm so jealous? She never wants to hang out with me anymore.