I'm sorry this is long but I need to vent...

I have a big family, six siblings. My two older sisters are technically half sisters but we all grew up together so I usually just refer to them as my sisters.

My oldest sister Melissa is 8 years older than me but she's so immature. She almost forty but acts like she's 14. She's overly emotional, to the point where my partner refers to her as chicken little. An acorn falls and the sky is falling. Everyone is out to get her. She's constantly late to family functions, to the point where if we're eating at 2 we tell her we're eating at 1 so she'll show up on time.

But the worst thing she does is the guilt tripping. Growing up we were never super close. We don't have a whole lot in common, and honestly it never really bothered me. However a few years ago my 3 younger sisters all joined the army and moved out of state, last year my other older sister Jenny move in with one of them as their live in nanny. Suddenly, we went from 7 living within ten minutes of each other to 3. My baby brother is super anti social, so it's just really Melissa and me.

Suddenly, she wants to be super best friends, because she's lonely. if I don't want to hang out or have other things to, she sends me a wall of text about how she's sorry she annoys me and doesn't understand why we can't be friends and she doesn't know what she did to piss me off. I'm like what....? Btw hanging out involves her coming over expecting dinner because she comes straight from work, and watching TVs until she falls asleep on my couch and I have to kick her out! I finally caught on that this is her way of manipulating me with guilt, and now I'm pissed.

Best example was my 30th birthday. My partner offered to take me and my parents (who are my best friends) to this super fancy restaurant. I made the mistake of asking my mom about it with her in ear shot. Suddenly she chimes in "that sounds awesome, I want to go" knowing the awkward position I'm in. I can't not invite her, that's not how I am. Now my BF is paying for the whole dinner for six people because of coarse her fiancé has to come. There's no way she can afford to pay for it because she quit he job the week before!

I'm so sick of her bullshit, she pretends to be this meek helpless victim to manipulate people and when I've called her on it she plays dumb. I don't know how to deal with her anymore. I'm so tired of being her big sister, I've never had someone I can look up to and go to for advice because she is so immature!

Vent over, thank you!