I just found out that my mother gave up a child for adoption what should I do?

Recently I discovered my mother had another child after I was born. My sister is 5 years younger than me. When I was 5 my mother moved away to Arizona from Ohio abruptly, I didn’t go with her obviously I was living with my grandparents. She’s always told me that she moved to get away from my dad who was abusing her. About two weeks ago I got a dm on instagram from my sister explaining asking if I was related to specific person and I said yea that’s my mom. She then told me that we were siblings. When she first messaged me I went to her page and thought to myself she looks like my mom. I’m confused on what I should do. She definitely looks like her and I don’t know if I should tell her or try see for myself then say something. She told me that she would like to have a relationship with our mother if she wanted too.

I just found out that my mother gave up a child for adoption what should I do?
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