Don't underestimate the distinction I'm trying to get you to make, FB. If your husband tries to deflect, just keep singing the same one-note tune, thusly:
H: "I'm not sure I can do that." FB: "I understand. That's something you'll have to decide. I just thought it only fair to let YOU know what I need from a husband going forward."
H: "That's controlling -- you're telling me what to do." FB: "On the contrary. I have zero desire to control you; it's mentally and emotionally exhausting, and I've decided that I can only let you know what it is that I need from a husband. Whether or not you feel you can BE that husband is entirely up to you. But this is what I need."
H: "You're telling me who I can talk to??" FB: "No, I'm telling you that I am no longer willing to live in a marriage where my husband continues to have contract with a woman with whom he had an affair, and isn't willing to do the things necessary to end that, and to be transparent enough with me so that I can feel safe again in the relationship. That's how I feel, and what I've decided is best for me. Whether or not you can do that, remains to be seen, and I understand if you can't. All I do ask is that you please be honest with me, and be honest with me if not today, then this week, because I can't keep doing this."