Should I Tell Him about my feelings?

About 20 years ago I met a guy online and clearly we must have exchanged email addresses as we've kept in touch over the years with the odd email, perhaps one, at the most two a year ... just good friends. However, my husband went into secure dementia care 9 months ago which I told this friend about. I already knew that his wife has dementia and he cares for her at home. We are on opposite sides of the globe I might add. Over the last two or three months we have become very much closer. We talk in Whatsapp for up to three hours a day sometimes. Our conversations are wide ranging, but we talk a lot about relationships between husbands and wives ... both our spouses have cheated on us in the past. We've discussed why relationships founder, lack of communication etc, the differences between the sexes etc and we are both learning a lot about how each sex ticks. However, I realise I am falling in love with him, but he has made it clear that if he loses his wife, he does not want a fixed relationship again. He has told me repeatedly how much he enjoys talking to me. He speaks three languages and likes the fact that I can help him with English. Just when I think he's going cold, he'll use an endearment that almost makes me flip. Should I tell him how my emotions are becoming engaged or just shut up and hope that eventually he might feel the same. Sometimes I think he does feel that way about me, but just can't see it.
Your input would be much appreciated.