select emails to forward

... I'd like to auto-forward auto-pay emails to my wife (but keep a copy in my own inbox)   

An email filter should be able to do that. On a desktop or laptop if possible, visit https://connect.xfinity.com and follow (gear icon) / Email Settings / Mail / Filter Rules. A filter something like this should work:

Apply rule if all conditions are met

Conditions

    Subject             Contains    payment
    Sender/From    Contains    Xfinity.com

Actions

    Redirect to           [target email address]
    Keep

"Redirect" means "Forward", and "Keep" should leave a copy in your Inbox. 

You may need to adjust the Subject and Sender/From values to match the emails you want to forward, and of course you'll have to enter the target email address that you are forwarding to.