I'm so sorry to vent but I have zero friends lol.

Ugh, so this whole week my aunt has been calling my fiancé and I just to tell him their car insurance is about to expire. She texted me last week and told me . I rarely ever call anyone back or even notice my missed calls , I am always running around like a chicken with its head cut off and my kid always has my phone on YouTube ignoring the calls that I never even notice come in. I didn't intentionally miss the calls or ignore her on purpose. I did tell my fiancé that night that the car insurance was gunna expire and told him the date . I then texted her back the next day and told her I let him know . I'm guessing he never called her back . He is exactly like me another chicken running around with his head cut off. He must've forgot to call her back too. So , on Sunday we took our daughter to a birthday party and she left me a nasty voicemail telling me why I don't pick up my phone and that why we are ignoring her that she's calling to speak to my fiancé about the insurance. So, I was super pissed about the nasty ass voicemail she left and I told him to call her back right then and there and to have her stop calling me about something that she needs to speak to him about. He called her and he told her nice and sweet hey please don't call her anymore about something that has to do with you and I . She flipped out and she must've not thought I was there and was like tell her to have her own balls to tell me (which I already did plenty of times) so since I was already pissed and I have held my mouth plenty of times I finally exploded and told her off then she tried threatening talking about I can start talking ( I guess saying she knows shit about me that she can tell my man) don't make me start talking . Which I told her start talking say what u have to say. I'm not very close to my family I am a loner . I am only close to my mom. My aunt and I have never really been close at all. Then this morning after she said all of the stupid shit she had to say she writes to me trying to clear her conscious saying sorry blah blah blah she puts me in the middle of everything . She got mad at my mom , because she had a friend she works with and she hangs out with she got jealous and stopped talking to my mom once and then wrote to me talking shit. She got mad at me because I am friends with my moms coworker as well and deleted me from Facebook and stopped talking to me. Some of my family is super immature . Well her grandsons birthday is this weekend and I was invited her daughters are just like her if she's mad at someone her minions will be mad as well . I honestly don't want to go , but I feel bad like if I am being petty if I don't go. I honestly really don't want to go . I always forgive her and act like nothing , but this time I don't honestly think I can forgive her . What would you do ?