Thank you for writing us here. I appreciate your sensitivity to your partner’s needs, and yours. I would suggest both you and your partner read a classic in the field, Stop Walking on Eggshells: Taking Your Life Back When Someone You Care About Has Borderline Personality Disorder.
I would also then ask the therapist that you have an appointment to see if you and your boyfriend can come in together for the first appointment. This way the therapist can give you both some feedback on what comes next.