Step moms cheating?

I'm sorry this is so long but I let out alot of details and other stuff she does so if u wanna no more detail just ask

OK so my step mom and my dad been together for 3 years and she wasn't a US citizen and to become one u have to be married for 3 years.now she went to two weddings in the same month so she was gone almost all month... OK now fallow with me, she got a new job that's like an hour away and she's the kind of person that HATES spending Any money and I think it's weird because it costs money to get there and because it an hour away she had been leaving for like a week at a time and come home for like a day or so and then leaving again, she's staying at a "girlfriends" house and I think it's bull shit.....she's 100% bipolar, she acts like a kid alllll the time and it's annoying if she doesn't get what she wants she has a hissy fit like a 3 year old... Another thing my dad accidentally opened her mail because he thought it was his and he found out she has like 10grand in a bank account that he didn't no about and she freaked out about it.... Something is not right with her and my dad doesn't see it ... She'll be texting me for like an hour and my dad will call her and she won't answer the phone but she's text me at the same time ....what do u guys thing