Lack of sex life

My husband and I have been married for almost 12 years. Been together 14.5 years.

We have 5 kids together.

We have ZERO sex life. He won’t have any of it. And it’s killing me. He doesn’t care.

He’s 47 and I’m 33 so I’m wondering if the age has anything to do with it.

But it’s killing our marriage. Sex is so important but how am I supposed to stay faithful when my needs aren’t being met? It’s been almost a year!!!

This is a reason why people cheat. Needs aren’t being met. And it’s so hard to not go elsewhere.

Any advice?