I'm Jewish and recently got a tattoo and my mom flipped....?

I wasn't originally going to tell her, I mean I am 20 years old, I'm a big girl, but I started to feel guilty because we pretty much share everything. Now I'm completely regretting it. She told me she wished I hadn't, that I've irreparably damaged our relationship, and that I may as well have stabbed her in the heart. I thought she might not be happy with it, but I had no idea that she was going to be so offended and take it like I meant it as a direct hit against Judaism. It's not like we're Orthodox, and she knows that I don't practice Judaism anymore anyways. We don't keep kosher, we don't do Shabbat, and our family has barely gone to temple in the last four years, if at all. It's just that she was a Hebrew school teacher for like six years and converted to Judaism when she married my dad. And for goodness sake, she's the one who spent $4000 on implants three years ago! My tattoo cost $70! Am I wrong here? How do I talk to her about this?