How would you counsel your FDW if she tells you that her husband is seeing another woman?

Listening is probably the most important thing to do here. I'm very, very cautious about giving other people relationship advice - it can backfire too easily. Be kind and empathetic and try and be flexible (within reason of course) if arrangements need to be made, such as a trip home.

Listen to her, try to calm her down and tell her to not worry a lot. Though she has to deal with this situation herself only so you can't really meddle with that. I agree with Roshni, try if possible that she is with her loved ones to ensure she doesn't take a wrong step impulsively.

Ask her two things: 1) if she's willing to work out her relationship with her husband, and 2) if she wants to end the marriage and/or sever her ties with her husband. Devise possible scenario which would benefit her depending on her answer.

Offer for her to take a break or swap maids with the agency so that she can go back and sort this out. Her personal problems might be an issue for her when doing her daily chores or when she is looking after your kids. Better not risk it

ask her to find evidence, it it turns out to be true, allow her to decide what she wants, and maybe you can can support her with some legal help

Devils advocate here - but how do you know she is really telling the truth and not just looking for a way to get out of a job?

Let her take off for a few days and make sure she is with people that care about her.

thanks

Be there for her and provide a listening ear.