In most fanfics Minho reacts normally to Thomas. Hugs him, tells him he understands, that Newt is in a better place, but to be honest, I think he wouldn’t really react like that.
I think Minho, first of all, would be flabbergasted when Thomas tells him and he’d be like. “What? You must be joking, right Shank?” and when Thomas tells him that no, I’m not joking. I really did it, Minho. I pulled the trigger and killed him Minho would throw something on the ground and scream some. I don’t think he’d throw some punches at Thomas, but maybe at a tree or a wall. Eventually, after he calmed down a little and thought about everything, he’d think that it is better this way. Newt wanted this. It’s not Thomas’ fault and he’d go looking for Thomas. They’d sit together, not talking for a while, and eventually Minho would open his mouth and say It’s okay, I understand.