I need some help? (Preferably from a parent or an older sibling) What would you do in a situation like this?!?

[Lily]

Talk to your sister first. Find out why did she lie. If she tells you, convince her to take that tweet back. That rumor could seriously cause your mom's boyfriend reputation. But if she doesn't tell you, tell your mom. But also tell her not to freak out and start shouting at your younger sister. Try your best not to let this tweet reach the ears of your mom's boyfriend. That would be really awkward. Good luck