She does not need pursuading how crap this has been for her.
Respect her decision to choose to save the relationship
When recounting her h's "explanation" for his infidelity, op didnt explicitly (or even implicitly) say she thinks it's bullshit, invalid etc.
She also talked about them being in couple's therapy.
Couples therapy is only appropriate for non abusive, honest partners with arguable fault on both sides.
Ops he's behaviour (going off the rails and leaving her to hold things together for their family/try to damage limit for their family) and infidelity could be seen as abusive (whether intentionally or not), and he's clearly trying to make her take responsibility for some part of his infidelity (because let's face it, "I felt unwanted" pushes the responsibility onto the other person to quite an extent). He has presumably convinced himself of that justification because it makes him feel better about himself ... Other posters have highlighted how little if any responsibility he has taken for his actions (in the other thread too).
His main focus on confessing infidelity bis that it's a load of his shoulders. He seems very selfish and manipulative.
All these factors made me as a poster wonder if op is being taken in by any of this bullshit or is blinded by their intimacy as to what he is really like .... In case that is affecting her decision to "work through" his infidelity (and other behaviour). And his behaviour around drink & drugs has apparently yet to be proven as resolved, as such, due to lock down, so that's ongoing.
Op's responses since then have clarified that she thinks she's not taking any responsibility for his infidelity so .... What more can any op say. I don't think it was unreasonable for anyone reading her posts up to that point on the thread to worry she's being taken in/manipulated by some classic cheater narrative and to try to point that out. Its possible op will still.clmr to feel.differently than she currently does, it's a long process to let go of an ltr/marriage.