I think the father of my sister's baby is our stepdad.
a friend suggested I use reddit to get advice because they give good advice so pls help.
my(18f) sister (23f) is pregnant and I think the father is our stepdad (45m). My mom (41f) doesn't know my sister is even pregnant. I know because I caught her taking the tests (she thought no one was home and decided to use the toilet with the door open). She went to a doctor and said she's 18 weeks pregnant. She didn't know because her period is irregular. She keeps saying she doesn't know who the father is, she was messing with a bunch of guys.
I know she's lying and the father is our stepdad because I borrowed his phone and did a little check to see if he's cheating on my mom lmao and instead, I saw very flirty messages between him and my older sister and he sent her a picture of his junk. She also stopped complaining about him entering the bathroom while she's in the shower. my dad (me and my sister don't have the same dad) also thinks there's something weird about my older sister's relationship with our stepdad, that it gives off mutual crush.
Idk if I should tell my mom because she doesn't even know that my sister is pregnant. I know my sister and mom are close but sometimes they have that weird frenemy relationship. Pls help and also is this illegal? will they go to jail if they find out how my sister and stepfather are related?