I would be upset, but I’d also be appreciative of the honesty. I think I’d like my therapist to be as ‘on the ball’ as possible, and if they’re tired and feeling like it’s impacting their work with me, it’d be a concern. You have no reason to feel guilty whatever you choose. I do think you should talk to work and see what they say if you think you can make the earlier slot work for you. I hate therapy before work as I find it difficult to adjust my head ready for work. There’s no good answer really, I’m sorry you’re in this situation.