You are presenting this problem as your personal issue and not as a problem with him or in your relationship. Given that, my perspective is that individual counseling for you may be more useful than seeing an Mft jointly.

What is the actual evidence that you have about this woman and about your husband? Starting with the woman: what has she done besides sit across from your husband that one time? Does she approach your husband in an inviting manner? What does he say about his interactions with her (if any)?

With regard to your husband: what is the evidence that he is interested in her or in any other woman now? How long ago was his womanizing?

You have done really well to stay away from accusing him. Good job! .

You might want to learn more about this woman. The mind runs wild when it has few facts to moor it. What can your husband tell you about her background and recovery? Does she speak at meetings? Maybe she is actually serious about her recovery (she was doing the literature work) and should not be labeled so quickly. Or, alternatively, maybe she is in fact specifically targeting your husband. What is the actual evidence, one way or the other, about her recovery and her intentions? Maybe on Fridays it would be good to make a point of learning facts with an open mind about this woman and her recovery. Remember that the mind can run wild when unmoored by facts. An individual counselor can help you explore and address these issues.