I'm sorry to hear you are having a tough time now. Yes, stress can often cause you to react the same way you did before. Dissociation is a coping skill that is normal for you, and if stressed enough, can be your default mechanism.

It is somewhat common for those who integrated their aspects of self to have that collapse a bit under intense stress. When you are overwhelmed, you find you need to segment your experiences to be able to handle them.

Please don't worry about going all the way back to the very beginning. I doubt that would happen. Worrying will cause you more stress, though.

Are you familiar with the steps of grief? Remember that you can be in a stage of grief and then go back to another and forward to one or be in two at the same time...they aren't really clear "steps" to grieving. Integration can be a bit like that.

IMO, you will always have a tendency to dissociate. It worked for you before. Unfortunately as you age, it will work less well.

Try and sort through the stressors in your life right now. See how you can remove or reduce as much as you can. Remember that it's all YOU and nothing foreign controlling you... but you have sent yourself a red flag notice to slow down and reduce your stress, imo.

Good self care is important, and I commend you on noticing that you are overstressed...if you don't think you can recover on your own, then call your T for a bit of support. Take care.