Talk it out.
1) Find out what your bare minimum requirements are so that you know where you stand. Be realistic about it too. If you want to stay with your wife it is very unlikely you are going to have a chat and suddenly be going at it hot and heavy every week.
2) when you approach her to talk, make sure it is in an environment that is conducive to an open and honest conversation. It sounds like you have been running on compassion and love for a while so perhaps you are already all over this step.
3) the goal of the conversation isnt to have sex.
The goal of the conversation is to communicate an understanding between the both of you. It is vitally important that you approach it with the aim of understanding how your wife is truly feeling. Open with your concerns "that it has been some time since you've both had sex and you are missing connecting with her physically" and then shelve your agenda. You can come back to it later in the conversation.
The goal is not to have sex, it is to understand why she does not want to have sex.
4) find a solution together. Maybe you will start small - find other ways to be intimate together without the pressure of sex getting in the way. This could be physical or non physical depending on what is needed. Perhaps she will suggest an open relationship, who knows. The important thing is that you agree and commit to your solution together. You can revisit and rework the solution as needed but whenever you do be sure that you have both given it your best go.
Sometimes, no matter what you do, things don't work out. Whatever the result I wish you the grace and fortitude to work through any hardships encountered.
One last note/request:
Research Asexuality. It may or may not help, I couldn't say. I'm suggesting this as there are many misconceptions around what asexuality actually is and the language used in the ace circles is actually really helpful in a broader spectrum. Even if it doesn't apply it may assist in the conversation in determining what is and is not applicable.