Well, OP, I am in the camp of "ask him what he thought of the note and see what he says". He's had some time to "digest" it.
If his response is "I'm not having a problem with the way things are" then you have your answer and can proceed from there.
If his response is "I have no idea where to even begin . I am completely blindsided by this and don't even know what to do or where to start" then you can proceed from there.
You can tell him that you think the marriage is too far gone to save and you wil be filing for divorce.
You ask him if he would be willing to go to counselling with you and work on this problem and improve communication on both your parts, because your skills could use some help too, despite Wishing's opinion to the contrary.

. Again, if he says "No I do not want to go to counselling" then you also have an answer, that being he is not willing to put the work into the marriage that it needs.
At that point, your decision is:
1. Stay in a marriage rut which will probably make you unhappy but you know what it is and what to expect
2. Stay married but develop a lot of outside interests and friends so that
your side of life is exciting even if his is boring
3. Leave him
I have no idea which of these should be your choice, as I have no idea about the details of your life. People choose to get or stay married for very different reasons other than the classic romantic "because I love my spouse and can't imagine life without them". Some people get or stay married because of finances, status, children, citizenship, cultural beliefs etc.
But really, OP, the time pussyfooting around this issue is over. You need to force some conversation. His response will tell you what you need to know, and then you can decide how to proceed.