Should I say something to my mom, or leave her alone?

My parents are in the process of divorce and I live with my mom. My dad cheated on her with this young woman at his office and told her to either accept it or leave (they used fight really loudly) so she left. My mom is a totally different person now than she was like 4 months ago. She used to be really quiet and meek and she totally depended on my dad. I don't think he was expecting her to leave. This may sound mean, but my mom was kind of what most people would call weak and now, its like wow, but some things about her are really starting to bother me. She's going out a lot, bringing home all kinds of guys, she just a bought a bike (motorcycle), and it seems like every time I see her there's a new tattoo or piercing. Its like she's not my mom anymore and its starting to scare me. I know she's hurting though. I mean, my parents' marriage was quite sad. Its like my dad was a dictator to her and now she has her freedom, but like I said she's scaring me. I know she's having her fun now and I don't want to wreck that, but should I say something or just let her go nuts?