Hi Jasmime, thank you for writing to us. My name is ***** ***** I'd like to help. I am sorry to hear your husband is so apprehensive about going to a sex therapist, especially when it is clearly very important to you. Sex therapists tend to focus their sessions on your intimacy and sexual health as a couple and as individuals and also on your relationship and it's dynamics. They have expertise in talking about issues surrounding sexual health and if certified, have training above and beyond what a normal clinician might have in terms of providing understanding sexual health disorders/problems and knowing how to help resolve them. Sex therapy is often "solution-focused" meaning there is a specific problem identified which is sought to be resolved by you and your therapist as a team. The problem at hand will determine the needs of you and your husband in the session and sometimes, the sessions can be focused on "hands-on" type of work helping you learn how to engage with each other in meaningful and pleasurable sexual ways, but most of the time will likely be spent focusing on communication enhancement and sharing of strategies to improve the current problem.
If your husband is not willing to engage with a sex therapist because of intimidation or because he is fearful that he will be targeted as being the source of the problem, offer him reassurance that you are in this together and are looking forward to an enhanced relationship with him. He may be intimidated because he is fearful his "failures" will be exposed so he probably really needs you to offer him support and encouragement around the issue, offering commitment about how deeply you care and how much you want to work with him. If you think this really is just a fear of the unknown, consider watching YouTube videos of some sex therapy sessions to at him at ease.
I hope this helps and hope it leads to your husband being willing to take this plunge and go to treatment with you! If he doesn't, you might go to a session by yourself to get some ideas for how to help the situation and to bring him first-hand knowledge about what is was like so he feels less intimidated and apprehensive.
Best of luck!