Helping my spouse recover

My husband was sexually abused as a child, by an older child. It's been 15 years and I'm the first person he ever told (a couple months ago) and he feels like he could never tell another soul. I am posting here because I can't talk to anyone I know about this because I promised him I wouldn't, but I'm looking for advice. He has ptsd from it and has suffered from depersonalization/derealization for the past 6 years and I firmly believe the underlying cause is largely due to this traumatic experience. How can I encourage him to begin healing? He is able to kind of talk about it with me but I want him to be able to talk about it with someone who specializes in trauma and dissociation. I wish I had the tools to help him process it myself but I just don't and I'm not sure if it's my place anyway. I just want him to heal so that he can feel normal again and to stop beating himself up. My mom went through something kind of similar and is comfortable talking about it and we both really want to know how she dealt with it but he doesn't want her to know his story so I don't know how to ask her. Can anyone give me some advice or some that I can pass on to him? He is greatly affected by this still and it breaks my heart that he's been carrying this alone for so long.