Letting go

How do I let the love of my life go , move on with someone else ? I’m not positive there is someone else but I have a feeling , we’ve been together for a year, broke up around our 9 months and still talk now. He isn’t the same man anymore and he was my first everything and it makes me sick to even think of him moving on and i just don’t know what to do, yes it’s toxic , no he isn’t the best guy for me I know there it better .. but I love him. So very much and I just need help on letting go , I’m home alone 24/7 it gets depressing, I just want him and only him I just feel there is someone else even though just yesterday we were all in love like “baby” and “babe, I love you” etc. we talk like that but today was not a good day for us and he said he was done putting in the effort for us just let whatever happens happen , and that makes me sad asf . I love him