I found out my ex is doing heroin and blaming me. I texted him about it he Denied it. I miss him

So me and my ex have been broken up for a year and 3 months we went out for one year and 6 months after we broke up I started to see him doing bad . I found out that he started to do heroine but he also blamed it on me . My ex and I have been through so much from us leaving together have a, miscarriage and our parents that didn't want us together. I truly love him but after our brake up he just changed so much and it hurts me, I want to be there for him but I don't know if I should , on New Years I texted him out of no where we were arguing I told him that I love him all he said was 'how can you tell me that you love me when you know you don't ' and he didn't want to talk to me because I did lie to him once but it was over a party so he said 'i don't want to talk to you because you lied to me' like what is he still hurt because of that ? well that was the last time we spoke. I love him so much and I still don't know why I don't hate him . Last month I found out that he got arested that just made me feel so bad . . I dare about him still more than he's own friends ever did . . I want to call him but I don't know if he would care or see if I truly do love him