Family Drama🙃 in Life Lessons

Ok I’m needing unbiased advice..
This is about my own family. Mostly my mom and sister.

Some backstory about my upbringing: when I was 16 I had bought an iPad and would message with a buddy from school (nothing inappropriate, just friends) my mom snooped one day and got onto me for texting with this boy.. I got grounded from the iPad I bought for a month.. since then my mom would snoop on my phone, read my messages and monitor who I talked to.

I am now married and live with my husband close by to my parents - yet they are too busy hovering and trying to control us to take care of their kids at home..

My 17 year old sister is a bullheaded, know it all that does what she wants and never faces consequences. My parents hardly see her and don’t ever know where she is or what she’s doing (she has more freedom at 17 then I do at 24 living on my own😕)

I wasn’t allowed to get Snapchat until I turned 18. When I turned 19 I met my boyfriend and would Snapchat him, later on we found out that after I would go to bed my mom would sneak into my room and open my Snapchats from him..

Some backstory on this situation: we just returned from a week long family vacation with my family and we shared a room with my 17 year old sister. On day 5 her and my husband got into it because she was being rude and ugly about us “barging” into “her” room.. it was a one bedroom hotel room..

Now back to the present: my mom came to me and told me that it’s my responsibility to fix things with my sister (since being home she has been snotty to me and not talking to me) she gave me the sob story about how her and her younger sister fought and she had to always resolve things.. and how my grandma and great aunt had problems later in life because it never got resolved. I told her that my sister is bullheaded and hard to get along with her attitude and my mom agreed and said she knows she’s a pain to deal with (tho she don’t try to parent her and correct her attitude?) my mom is worried about our family Christmas vacation and says it will be so awkward unless I fix it..
I told her I didn’t do anything to deserve her snotty attitude. My mom said I need to just pretend nothing happened and go back to normal (she basically wants me to just pretend I’m ok with her attitude so my sister won’t have to face any consequences..)

I told my mom I’m worried about her because she’s talking to 50+ guys on Snapchat at all hours of the night.. my mom said she’s not concerned or investigating because she’s never gave her a reason not to trust her.. (but I did? I’m more trustable..)

The only reason she thought I was untrustworthy is because she snooped.. and found something she didn’t approve of.. but she says she would never invade my sister’s privacy like that…

When I lived at home I spent a lot of time with my parents in the living room.. my sister locks herself upstairs and never sees my parents and never lets anyone upstairs including my parents.. (it’s their house tho?) my parents never know where she’s at or what she does.. yet she’s more trustworthy?

So is it my responsibility to “fix” things with me and my sister?
Do me and my husband keep telling my parents indirectly to parent their daughter at home and get off our back?
Do I argue about how they treated and continue to treat me as tho I’m untrustworthy (it made me mad that she basically said I’m untrustworthy yet my immature sister is trustable..) ?

Any advice is appreciated.. I’m drowning in this mess..

There is so much more that has happened recently but I was trying to keep it shortish🙃