Help on high contrast dynamics

I am looking for advice on navigating a complex D/s dynamic. My girlfriend has a severe humiliation fantasy rooted in past relationship trauma where she was treated purely as an obje_t by exes. She wants to reclaim that by having me "s_ll," "g_ft," or tr_d_ her trans__tionally in roleplay to maximize her feelings of obje_tif_c_tion. Crucially, she is a lower-limb amputee and explicitly requests that I us_ her disability during scenes. She needs me to verbally mo_k her mobility limitations and "desperation" to trigger the shame she requires for arousal. The play is extr_me and includes "watersports" and fluid cons_mpt__n. The challenge is the "switch." Outside of play, she has a strict boundary for the complete opposite treatment. Because she never received genuine care from her exes, she needs me to be a supportive, romantic, and reassuring partner in daily life. I am struggling to balance the "ruthle_s" persona she wants during sex (especially now that she wants to transition these fantasies into actual group play) with the loving boyfriend she needs me to be afterward. How do I maintain this extreme split without emotional burnout?