Should a president be impeached for lying about an extramarital affair?

NO- let the voters decide at the next election.

Or should a leader’s personal life not interfere with their ability to govern?

They should NOT let their personal life interfere with governing

And Monica — was she a victim or a willing participant?

Participant! She knew what she was doing. In her memoirs she even wrote about how, when on her knees with his penis in her mouth, how she felt this deep connection. Uh okay. And who keeps a stained dress?

She isn't totally blameless but neither is Clinton- he used a power imbalance and I have no doubt if it was not Monica he'd have found someone else to cheat with