I want to end affair with my brother-in-law but threatened by him

I’m residing with my parents and my sister’s household, and my brother-in-law and I developed an affair which involved physical intimacy. Acknowledging my numerous errors, I attempted to halt the affair by threatening to expose us to our family, though it was merely a bluff.

In fact, I tolerated the situation, fearing the upheaval it would bring to my family and potentially dismantling my sister’s marriage.

Initially, my brother-in-law consented to cease his advances, and I believed we could move past this. However, my engagement in a new relationship provoked his envy. He abandoned all reason, pressuring me to end the relationship, adamant that I shouldn’t be with anyone else.

He admitted his selfishness, confessing his overwhelming love for me and his inability to forget me. He wept before me, expressing moments of not wanting to continue living. He desires my presence constantly, otherwise, he’s resigned to letting our secret come out, accepting whatever may follow.

The thought of bringing shame upon my family is unbearable. I deeply wish to avoid the disintegration of my sister’s family unit.

Currently, my brother-in-law professes his love to the extent of losing sleep. He seeks clandestine meetings, messaging me whenever possible. He claims the pain of seeing me with someone else is unbearable, insisting he’d find existence meaningless if I were to leave. At times, while driving and pondering over me, he considers ending it all, believing it would spare his wife and me further anguish, he said.

I’m at a loss on how to compel my brother-in-law to forget me and maintain distance. My circumstances prevent me from relocating, so I find myself in a dire situation, mentally anguished, dreading the scandal’s exposure and the ensuing disgrace.

The clandestine relationship with my brother-in-law cannot persist, because its discovery is inevitable. My desire to detach and cease loving my brother-in-law is paramount, but his presence instills immense fear in me.

What should I do?