Bed-wetting after my ex husband tried to kill me

I was in an emotional abusive relationship for 3 years and all my kids saw how this man would treat me. My boy obviously wanted to protect me so anytime it seemed like my ex husband was gonna hit me he got in between us. My ex would usually push him out of the way and pull on me. But he hadn't hit me, hit me yet. I think my son felt like he needs to protect me because his dad was murdered and he feels guilty that he slept through it e en though he was 5 at the time. 3 months ago my husband hit me and my daughter and son tried to stop him. But he started beating me and my daughter ran outside screaming for help and my son stayed. I remember my ex choking me and then going unconscious. I woke up in the hospital. I put a restraining order against my husband and filed for divorce. All 3 of my kids are in therapy. My son wet the bed one night and I didn't think anything of it. Then it was another night and another and another and it's been everyday for 3 months straight. His therapist thinks it's stemming from not only the trauma of watching me get beat to death but it brought up guilt from losing his father. He's almost 17 and he's tall so his therapist said he probably feels like he should have been able to protect me. I have tried not to make a big deal out of it. My daughter has found it"funny" but I nipped that shit in the bud right away. I understand there isn't much I can do besides therapy and or possibly diapers. I just wish I could offer more support so he can feel safe and hopefully stop bed-wetting. Has anyone been through trauma bed-wetting and what helped you?