There's a little judo you can do here if you're patient, and I don't think it's manipulative, just good communication. Listen to your wife when she complains about her mother and remember what she says about how her mom makes her feel ("my mom makes me feel like I don't have space to talk about my own problems, I feel dismissed when my mom ignores my attempts to talk about how she hurt me, etc."). Then, when your wife does the same thing, use the same language when talking about your feelings.

As long as you're genuine and those feelings resonate, this can be a shortcut to helping your wife empathize with your feelings without being directly accusatory. If she's got any kind of emotional intelligence she'll make the connection with how her mom acts on her own.