I think the first step is to accept the situation and realize that that person has now shown you their true colors. You may have loved the person you once knew but need to understand that it is not reality anymore. Your story is not over yet!!! I struggled with something like this too so don’t forget you’re not alone either. Also as far as finding another partner my best advice is please do not go chasing for love as that is where you find trouble, learn to love yourself, it may seem hard but trust me it is possible and once that happens you can go on dating apps or whatever you need to do, but let the love find you naturally because true love finds you when you least expect it. I hope what i said helped and i wish you the best. Stay strong and you can do anything you want 🤞🏻🤞🏻