Is it correct to continue with psychotherapy & talking about the past while i am in a relapse?

YES!: Please continue your psychotherapy. I am assuming you mean drug or alcohol relapse (or maybe sex or gambling addiction). It is best to continue your therapy. You should be able to focus more on the present about your relapse than just focus on the past, if you have a decent therapist. Sometimes you should still talk about the past if it is a cause of why you relapsed/

Uncertain: I don't know the relapsing condition. Is it substance abuse? If the talking therapy is causing you to fall apart then it may be more than you can handle at this time. It is the therapists job to manage your treatment so that you are not REGRESSING too slowly or too quickly. If you are in a bad place, it would make sense to address the here and now and allow you to stabilize before going deeper.