My 14 year old sister is dating a 22 year old dude

I think you read that right. You can double check. 

Actually, I didn't know the guy was 22, I thought that he was her age... I could see that she liked him a lot, calling him really late (because they met on the internet). She even added him on the Snapchat group "we" (my siblings and a few cousins) have. 

I am gonna call the guy M and my sister N so they can be M&N('s). 

I added M back on snap cause I was like "yeah okay he's my sister's friend and he's polite". Then my sister told me he was 22. I was FLABBERGASTED. I told her something like "that's not good" because I FREAKED OKAY??? N then started to act like super defensively and telling me to stfu. 

Then M answered a story (with a pic of me in my new year's outfit) and he responded back with a BAGUETTE????? IDK what that sh means so I asked him, but he gave me vague answers. Then I asked him THE question. 

"What are you and my sister?" 

And he dared respond to me with eyes emojis. 

I asked again and HE TOLD ME THEY WERE DATING. Hopefully the guy lives in another country... But still. I went full on "protective big sister mode" and told him I was worried because I KNOW, I can SEE, that she's not mature. he answered back with "I think she's mature for her age". ARRRYIRDFFRODUGLGLDGB WHAT ARE YOU ???? NO THE F SHE'S NOT. 

We kept talking and he got offended or smth ( I wasn't even mean, i could have called him a certain word... but i didn't, I just expressed my concern with the prettiest words known to this world) and send everything to my sister and acting like a baby and a victim. 

The next day my sister showed the screenshots to my mom, whom (or who idk) said, " you should have never told her" and that "My worry was out of place". LIKE excuse me???? 

Plus, it's not like she freaked out when my other sister (who was 15-16 at the time) told us that she had a crush on a 21 year old man. It was a guy from her judo club and my mom was mad about it. BUT HERE???? SHE LETS MY 14 YEAR OLD SISTER DATE A FREAKING 22 YEAR OLD MAN???? 

So, all that to say that I am confused. I am 18 and i wouldn't date a 14 year old. I feel weird, cause I see them facetime and the dude is older than me. Plus, I am holding the drama so I can say it face to face to my close friend that I see soon (luxury drama, with pics and all)

I don't know what it supposed to be a blog but it's gonna be my drama trash or smth. Anyway it's like lots of things happen in my life. 

Sorry if my English is shitty.