Success negotiating more WFH as counteroffer

Hi all, I know what I would tell someone else in my shoes… But I am emotionally invested in this situation and frankly not objective.

Long story. But my newish (just under a year) supervisor pressured me into temporarily giving up my one remote day per week and staying late every day. I complied, but started searching. I now have an offer on the table at a new place and am negotiating the details including WFH. While my supervisor is new, I have been with my employer for nearly 7 years. WFH has been a major controversy throughout the org, but I’ve had one day wfh for most of my time there, which is a schedule I can live with. 5 days a week on site, leaving at 7, is pure hell. And now that she’s done this to me once, I’m afraid she will demand this again

My boss has already said this schedule from hell will ease up soon, and I can go back to WFH but TBH I don’t trust her. I told her that I couldn’t continue at this pace in response to when she said her ‘worst fear’ was me being poached by another employer… I’m going to approach her once this offer is firm, and attempt to counter a more flexible schedule. I’m not interested in more money. In fact the new job is a pay cut….has anyone been successful in this sort of negotiation? Hell, tell me if you haven’t been successful! I need to know everyone’s experiences bc I have my own thoughts, all clouded by my rage at being pressured into RTO and late hours. Thank you all, in advance.