Ranting, ugh. Disappointed. Advice?

[Mz.Nana]

So my bf's little sister has only had 2 bf's, she's fifteen and I give her advice cause I've been through every kinda of relationship there is with as*holes, cheating to abusive. Done it all.
Well anyways. She asked me for advice cause her boyfriend of less than a month is being a complete as*hole. I told her he wasn't worth her time and to break up with him. he's been cheating on her. Agree that she's wasting her time??
Well she ditched school on Tuesday for this guy and got her belly pierced. Me, my bf and her sister are sooooooooo pissed and disappointed. I really just feel like smacking her cause when her mom finds out she's going to kick her as*
We told her we wouldn't tell her mom but I'm sooooooooo tempted to tell her mom just so it puts an end to everything. She was the most innocent girl up until a few weeks ago when she got with his guy. And I'm worried it's going to get worse and I really don't want her to go through things I went through. But because I've been through it she's going to have the same mind I did and be like "no it's not like that." and all this other bullish*t.
Ugh. We dunno what to do...

[Proud Band Geek]

If you think this guy is putting her in any danger then you should definitely tell her mom your concerns. She's your best friend and if she would do anything for you, then you should do something like this for her. On the other hand, if the guy is just a cheater/liar/jerk/etc, then you should keep quiet and eventually she will learn either a) to trust your opinion more and what you're saying or b) she will learn from her mistake. Hopefully both. Hope i helped!

[jade_butterfly_lily]

Sounds like you are being torn between being a friend or an adult figure. If you don’t think the guy is good for her, tell her mom. Also, if she cut school and got herself pierced, tell her mom. She may hate you for a little bit, but maybe some grounded time without this guy would let her see that he isn’t very good for her.

[Andreia]

It's best to let people make their own stupid decisions in life even if you've been through the same things they have. She should learn from her mistakes on her own, because by telling her what she should and shouldn't really do will make her want to do it more ya know? :/

[****]

Hey I had five piercings and a huge tattoo covering my whole upper back by the time I was fifteen be thankful she isnt like that! Shes fifteen and growing up let her be and learn the hard way. If u dont shes just gonna rebel and hate all of you. She will learn and let her stick it out with this dude so she knows what guys not to date next time. Dont get mad at her be understanding or she wont tell you anything.