1. As @Timzii suggested, I tried setting game to borderless. It didn't fixed the problem at all, but once the game started freezing, I was at least able to close the game this time (in fullscreen, I literally had to restart my pc lol).
2. Another thing I did was set "Accelerated CEF Rendering" to ON and "Windows Notification" to OFF on RageMP settings.
3. Then I set Texture Quality to Normal, because I noticed that the game started freezing when I was going a little bit too fast with the car, the game basically was struggling loading streets and other textures in general, doing this fixed the texture loading problem. (this is a common issue even in FiveM)
4. What really did the difference tho was deleting & re-downloading the server resources. In RageMP folder, under "C:\RAGEMP\client_resources", just delete the folder with all those numbers. Then reopen RageMP and try to enter GTAW, it will download everything once again.
Now the game is running perfectly. I don't know if set back to fullscreen will destroy everything again, but as I said, the major thing was redownloading the server resources.
Thank you so much @Timzii and @Paenymion for helping me! ❤️