Just to give context by saying that I have struggled with depression/anxiety since the age of 5 (now 37), have been in my current role for six years and have only had a handful of days off in that time for this reason. I've accessed a fair bit of therapy in this time and work have always been supportive as long as I make sure that I make the time up (I usually do a few hours unpaid overtime every week anyway).
I have the opportunity to access a therapy group specialising in trauma, specifically for survivors of domestic abuse, rape and sexual assault - I was in an abusive relationship for many years, and didn't until recently really click on that what he had done to me was rape and assault. My boss and head of department are aware, but not of the full gory details. Group will be 2 hours a week for 12 weeks and in work time, but Head of Department was supportive of me attending for my own health and wellbeing.
Asked direct line manager after they've returned from leave... the first session clashes with an event that I'm not leading on (I have my own one to do without any other team members supporting me) and for which I've written the slides for others to present, so I won't learn anything new either. She asked if I could miss the first therapy session - I checked, and I can, but don't see why I should. I let her know that I could miss it and was happy for her thoughts, again she highlighted the event - I feel like I'm being blackmailed slightly and don't know where to turn! Head of Department is on leave and have contacted my HR link for advice but no response and obviously a decision needs to be made.
Just to add this isn't the first time she's shown a total lack of empathy, it's a fairly regular thing. For example a few years ago my aunt and cat died over the same weekend and I took the Monday off as I was exhausted/wrung out - her exact words were 'I hope you're not going to make a habit of this?'
Any advice on what to do? I feel like if I go to therapy and miss the event she will hold it against me and I'm currently trying to put myself forward for the next stage in my career and make a good impression...