Complex sentence: The experience of the therapist is also very much part of the therapy: since we are co-creating our self-other experiences, the way I experience being with the client is significant information about how the client experiences themselves.
Split into simpler sentences: The experience of the therapist is also very much part of the therapy. Since we co-create our self-other experiences, the way a therapist experiences being with a client is significant information about how the client experiences themselves.