"This guy should have just laughed it off with his buddies. Being tricked by a transvestite isn't the worst thing that could happen to you. Just get over it."
The fact that he overreacted as strongly as he did suggests to me that there was more going on than we know. I'd guess that he "knew," and was only OK with it because everybody thought he was with a female. When "she" was outed as a cross-dresser, he was as well. We're dealing with Latino culture here, remember. Homosexuality would be a big problem, hence the cover story. He had to kill "her" to keep the truth from coming out.
This explanation makes sense to me. The killing doesn't, though.
El Dorado County is at least a 2-3 drive from where the murder occurred. The murder also occurred, not the night of the sexual encounters, but some several days afterwards.