Jealous of friends new friend (yes I know, it’s pathetic)

[Pettyspaghetti]

Not so much of an AIBU as I know I’m being so immature and pathetic. I just want advice on how to get over it!
So my friend (I’ll just shorten it to BF) has made a new friend via her DC at school. BF has been seeing her new friend (I’ll call her sally) a lot recently. Last night BF invited sally and her family to hers for a piss up, I saw a lot of it on social media and it got the green eyed monster well and truly going
I’m not usually jealous of BFs other friends, but this one has made me feel like a school girl. I’m in a foul mood whenever I know they’re together, and feel like I shouldn’t talk to BF when Sally’s with her (not that I get a reply anyway).
Please give me some advice to snap out of this? I feel so stupid for being jealous! I think I feel threatened, but I really don’t know why! I’m not the most sociable of people, and I prefer it that way, and I never get jealous if BF is with other mutual friends. Could this just be down to PMS? I know it all sounds very trivial and I sound like a silly little girl (I’m almost 30 ) I want to get over this sooner rather than later, as BF isn’t stupid and will figure out soon that I’m being a massive drip!
Any tips or advice on how to woman up and get the F over it? Please go gentle on me

I really like that kerala, it's a good quote to live by I reckon.

@moanaohnana a puppy after the crumbs of friendship is exactly how I felt! Asking her to try and squeeze me in here or there. Depressing.

3's especially 3 women friends together in my experience dont work well. I would want to be invited to things with both of them together.
I also wouldnt discuss it with BF, I wouldnt give her that satisfaction of seeing you are bothered. She knows what she doing.
Instead I'd get busy doing other things, go out more with your husband and family, join groups, classes, the gym, anything. Dont be hanging around waiting for her.
If she asks you to do something them tell her you'll get back to her as your not sure what you have on for that evening.Dont treat here like a priority when your a low grade option for her.

Do you have children OP?

Yes...I do like that saying;
"Never make someone a priority if they'll only make you an option."
It's a great rule of thumb.

I don't think your bf is doing anything wrong but it is an indication that she is expanding her friendship circle now and you should try to do the same. Friendship doesn't come with a contract...it doesn't even come with any obligation...it's something we choose to have because it suits us at the time, it's not something we are either beholden or entitled to in the long term.
The key is not to put all your eggs in one basket but to keep busy and to always remain open to other offers. This way, should your chosen 'BF' branch out, you're not left behind with no one to play with. The aim is not to have a 'best friend' who you rely on for company but to have a few friends that you enjoy spending time with. This way you are less likely to feel wounded by your pal choosing to hang out with someone else...which is actually perfectly acceptable.

P.s I only understand all this through experience OP. I have been hurt in the past too. I invest far less in my friendships now and I'm all the happier for it.

Please can you tell me when you figure it out? This happened to me at 15 and I still struggle to let myself get close to any friends. . My best advice would be to throw yourself into a new challenge or interest, make a future arrangement to see BF and get on with being you.

Thank you all for the replies, there’s a lot of solidarity on this post and although we’ve all been through shitty situations friends wise, it’s nice to know that other people feel the same way.
I have 1 DD, she is the same age as bfs DD and they get along great!
I can see how having a school Mum can be easier, as she’d see her every day etc. Whereas I don’t get to see bf as often.
I don’t think Sally likes me, even little things like how she’ll “like” things my friend puts on Facebook, but then if bf posts anything to do with me she won’t. And she’s started tagging bf in posts about friends/best friends etc. I don’t know, i know this all sounds terribly childish. It usually doesn’t bother me that my friend expands her social circle as she’s much more sociable than I am. It’s just this Sally!

Sally is feeling possessive over your friend and hopes to replace you in her affections. She is clearly insecure and feels the need to create a competition she can win in order to feel worthy. I know this because I have experienced very similar.

Unfortunately, the worst thing you can do is entertain the competition by competing as her drive will undoubtedly be greater than yours and with her being the shiny new exciting thing in your friend's life, she will annihilate you, effectively destroying your friendship with your friend. The best thing you can do is be disinterested in and unbothered by it, glibly continuing on as you always have done and not letting her annoy you to the point of fighting back in a friendship tug of war with your pal in the middle. So long as your conduct is impeccable, Sally (and in turn your friend) can't accuse you of anything untoward such as jealousy or possessiveness. Leave that to Sally...let that be her gig. You find other things to do and people to see...which is what you ought to be doing anyway. Now is the time to spread your wings a bit and let them get on with it. Your friend will have far more respect for you in the long run if you do.

Petty - that is exactly the kind of thing that happened to me. It sounds so trivial written down but it really hurts! To this day, I have no idea why our Sally took against me. I even had a thread on here about it years ago, when Wendy/Wendy-ing was a big thing.

Hi all , I’m so happy that I found this post I feel so embarrassed but I feel I need to talk to someone. I’ve known Sarah for 18 years , we have always got on , but the only thing I hate is her always trying to be competitive with me , with absolutely everything 🙄 what ever I want she will go and get it first or if i say I wanna decorate my place like this she will go and do it how I said I wanted to do it. I got myself a job and also got her a job too. I then left that job (cleaning job) and went on to be a carer. I got her that too. I then left that then she left. She went back to the first one and now all she talks about is Sharon , Sharon this Sharon that , Sharon is a laugh etc etc . I always say I’m happy for her but never does me she’s very contradicting as well which annoys me so much . She got into so much debt recently and had to declare herself bankrupt. But recently she’s doing it all again !!! She’s got herself 2 contact phones today which she dosnt need , one for her and one for her partner. I feel so silly sometimes but it annoys me. I haven’t got much friends and she knows this. When’s she’s with Sharon she dosent talk to me only when she’s on her own. I’m 35 years old and I feel like a twat. The thing is she’s 42 and her new friend is a lil bit older. I love reading everyone’s stories cause I know I’m not on my own x

Reading your OP, I can see that you aren’t a jealous person by nature or feel that way towards any other friendships. I am inclined to see that there are some toxic dynamics going on with your friend playing you off against this new friend. She sounds at best very tactless but potentially gets off on making you work harder or fight for your friendship. Sally appears to play right into that. I am rather stubborn and would distance myself and spend more time with people that value you.