Was I being to hard/harsh on my cousin's kid?

My cousin, her 3year.boy, and her 8year.girl moved into our 3 bedroom townhouse with my family of 5 (my mom, dad, 2 brothers 17yr and 10year, and me 18yr.), because she had a huge fight with her boyfriend/husband (they are not married but have 2 kids) for the third time. So I gave her my room and I slept on the couch, but a week and half later she went back to her guy. My mom told me that she said I was being too harsh on her kids that's why she moved out.
Was I being too harsh on them because don't let them use my laptop, didn't let them yell or run at 6:30 in morning, make them clean after themselves, make them drink more water instead of pop and juice, told them to say please and thank you, didn't let them have candy or cookies in the morning and to respect their mom more.
or is she just a bad parent letting your kids do what ever they want? Her 3 year old screams and shouts she gives him her iphone or anything he wants and lets him hit/bite her and his sister and throws stuff at her too. Then her 8 year old boss her around, she leaves the house without even telling her mom nothing, she lies all the time, and her mom buys her anything she wants (she a phone, DSI, and a ipod). Then she's say that i'm to young to understand, what you guys think?

No you are right. I can't stand people who don't discipline their children. I definitely would not be tolerating biting or anything else out of line. I'm a very strict parent and i do not play when it comes to discipline

You were being too harsh and she's probably a bad parent. The two are not mutually exclusive.
Some of the things you did are acceptable I think as long as they're age appropriate (a 3year old can only clean so much, etc), but it's definitely none of your business what/when she lets them eat or how she lets them treat her.

No. You're not being too harsh. You're just stirct.you're just being strict because you care for them. I think that your cousin has a bad habit towards parenting. I'm 20, my cousin also leaves her 6year old child with me when she goes to office, I'm also like you, not letting him borrow my ipad, didn't let him to run around the house.sometimes, we even shout at each other and then, he will go to his mom saying I'm being harsh to him, but his mother (my cousin) understands me, she even gets mad at her child when she founds out that her son did something wrong.

Your mom and your sister have a co-dependent relationship, and your niece and nephew are spoiled rotten brats. You weren't too harsh, your sister is a limp noodle when it comes to disciplining her children.

I think it's remarkably unlikely that all these adults stood around while an 18 year old disciplined someone else's kids.