Hi there,
I am an independent advisor and a Microsoft user like you, and I would be happy to help you out with this.
Unfortunately there is no iMessage compatible application for Windows. However, you could use other third-party applications which are multi-platform.
A couple of examples would be Facebook Messenger, or WhatsApp - which are accessible through a web interface on Windows.
For example, if you are a WhatsApp user, you could log in on your computer at https://web.whatsapp.com
Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.
I hope this has helped you. If this is not what you are looking for, please reply and let us know and we would be happy to look into providing some different suggestions!
Regards,
-Ashton