I've tended to keep therapy appointments when possible right before major events, and it's tended to be helpful. I think as long as your therapist is aware of the stressors your dealing with and is skilled at their job (granted, that is not a given!), it's a useful thing to have some help talking through what you have going on and containing those stressors.

So for example, I contemplated canceling a therapy session that happened to end up scheduled immediately prior to a close relative's funeral but decided to go, and I was glad it worked out that way--my therapist helped provide an outlet for that grief while also gently allowing me to process some ongoing issues in session alongside the immediate stress, but he knew not to push for anything deeply buried or contentious while I was dealing more immediately with that major loss.

I also kept my therapy appointment the day before my wedding! And obviously he knew not to dredge up anything heavy in that moment, and let me take the lead even more than usual in steering the topic wherever.

So yeah, I think it can be helpful to still go, but maybe explicitly mention to your therapist that you don't think you have bandwidth for the painful ongoing big topics in these upcoming sessions?