How sad~my suggestion would not to try to rehome him yourself and to contact a rescue in your area. Rescues will make sure to rehad before trying to rehome so that things like are less likely to happen. I have seen things like this happen on YT where people have tried to rehome on their own and the pup comes back-more than once. In the mean time, I would keep him on a leash at all times so that you can control his behavior.
I am wondering if he was guarding something or if something else was going on. Was she coming toward you? Food? Bed? Many times someone says that a dog is aggressive but really it is guarding.
YHR does not have any foster homes in your area but you might try to contact YTNR or UYR. My suggestion would be to surrender to a reputable rescue who would be willing to work with his issues and find a home with a good fit to his personality and issues. I'm so sorry that this has happened and is one of the biggest reasons that many times you will see members here suggesting contacting a rescue vs trying to rehome yourself.
