Stupid but I can't help it. 😡😤

Kayla • 20 with the most perfect family. Blessed with one handsome husband and one perfect little chunky 9month old baby girl.
My mom divorced my stepfather 4 years ago. We are still very close as he raised me my entire life, because my father was never around. Anyways his niece and I are a year apart and we used to hang out and talk everyday, but I don't agree with the ways she acts so we stopped hanging out as much three years ago. Recently she's popped back into my life as she's 18 now and has a car so she just comes and goes as she pleases. She had a boyfriend for two years and had shared with me that he was controlling. She then started coming over to my house everyday because her mom trusted me, but I found out why she was coming over all the time. At first I didn't mind hell im pregnant and newsflash to me not one of my "friends" talk to me anymore because they can't party with me anymore. Anyhow I found out she had been lying to her mom about where she was staying at. She was cheating on her boyfriend and using me as a cover up! I figured all this out when she said she was gonna drive to see Blake a guy she met online who lived 4hours away and asked if she could get a picture of my ultrasound to send to her mom because she left at 7am and told her mom she was going with me to the baby doctor. I brushed it off and sent her one but then it was like an every week thing.  She would call me while she was getting off work and say that she was heading to some other guys house and if her mom called my phone she was asleep. Caleb her boyfriend read her texts and seen the pictures and videos of her cheating and they broke up. But she continued to use me as a cover up for her mom. It finally pissed me off to no end when she asked me if she could bring the boy she has been driving hours to see and stay at my house with me and my husband for the weekend. I said dude just tell your mom the truth I'm tired of you using me like what if you wreck driving there or something happens I won't know what to even say. So she eventually got the courage to tell her mom. Hasn't talked to me since then other than a snapchat of her and my ex boyfriends little sister and this comment on Facebook(picture posted below). It's annoying that she is calling herself aunt? But the fact she said "OUR" baby gah it just I can't help but get irritated. Like no me and my husband laid down and this is our baby girl! I am irritated by the fact she used me and when I confronted her about it she stopped talking to me again and now she's claiming "OUR" like she has some kind of rights to this child. She called me after she commented(which at the time I didn't see what she had commented) and said she wanted to be in the delivery room when she's born too. Which I had made 100% clear to everyone it was going to be just me and my husband. This is a moment that we both want to cherish. We can only have two people in the room and it's not fair of us to have one person over another so my husband had the idea of it just being us. We won't tell anyone until after she's born so we can enjoy her first and I can try to breastfeed and get some rest. We will call the family and let them know when it's their turn to come so we are crowded or too overwhelmed at once. My husband told me to let it go, don't say anything to her about it. But it is absolutely annoying.