Need advice don’t know what to do

My husbands biggest wish is for just everyone to get along and I keep trying to explain to him in today’s day and age everyone has there own opinions and everyone is different so it’s very likely for some people to not get along.

I feel like I’m one of the coolest people always happy and always ready to get together and have a good time.

However I feel like my SIL HATES me. I don’t know why but we’re all girls we have vibes. Since I got married to my husband I feel like I was buying my SIL’s love. Like with gifts always buying her little stuff giving her clothes that I wouldn’t wear buying her cute purses to have and she’s like 10 years older then me. If there was a wedding I would open my closet for her. Do her hair and make up because I felt like she always felt insecure. So I would te her let’s get our nails done let’s get pedicures. But I would always catch her badmouthing me to other people especially my husband. And then my husband will say stuff to me.

I keep telling him to open his eyes. And see the real picture that at least I’m trying. My husband is from a diff country and I’m American but bilangual to the language and sometimes I feel like maybe she doesn’t like me because I’m American. The only time she ever ever texts me is if she needed help with something like paperwork that she didn’t understand. And me trying to be a nice SIL off course I’m always helping.

I’m just asking for someone’s opinion and like what should I do. When I take a step back she still complains and it’s so annoying.