It sounds like your husband had decided you and him are over in the respect of making your sex life work,do you think he is making it with women outside of your marriage?You say he stays out late and for days at a time.It does seem like he hs found love elsewhere or sexual gratification of some sort.

Can you face it if your marriage is over?I am sorry if this is hurtful.
Don't you deserve a man who will help you overcome your sexual difficulties and be willing to work on them with you together and in therapy?You are still young and deserve that,if not with your husband then with someone else.I hope you can face the future whatever comes with a view to focusing on your self and what you need and deserve.