There’s a fine line between wanting to be with someone and not being able to stomach them being with someone else.
Are you really in love with her or is the idea of her in his arms sickening? We need to ask ourselves this and stop forcing our hearts to feel love that’s already lost. Of course, it’ll hurt but it’ll hurt more if you’re holding on out of pride, selfishness and jealousy.
Let things naturally unravel. Maybe it’ll work out someday. Maybe it won’t and it’s the end of the road. Learn to be ok with that. Your heart will thank you later.