Should I tell ex about the baby.. long read

Ok so last year around this time I found out I was pregnant, my ex and I decided to take a break before I even found out about the pregnancy. His reasoning was that he had family problems and had to go to mexico for a few months. around the time I found out about my pregnant, he told me he had came back for a few days ti handle some things here before going back to mexico. I saw that night but I didn’t mention the pregnancy because I was thinking of how to surprise him and make it special. Two days after I saw him he asked if i wanted to go away for a day and just be together before he went back so we were planning that out but to my surprise I got a call the very next day from a girl. She told me that she didn’t know what was going on between us two but she had been seeing him for 2years. Him and I had been “dating” for almost 3years so I was furious, and then .. she told me she was pregnant and wanted to let me know so I could leave him alone.. My heart sank.. Not only did he cheat our entire relationship but he was also expecting a baby and from what she told me we both got pregnant at the same time ): She was a week less in her pregnancy compared to mine.. I told her I was pregnant too but that now I didn’t want anything to do with him that i was done and if she was smart she would leave him too.. A few hours go by and he kept calling me and kept asking me if i was pregnant and why i don’t tell him and that we could work something out. I was devastated, I was mad, sad, I felt betrayed I didn’t know what I was feeling. In one of those calls I told him to leave me alone because the baby wasn’t his and that I had cheated on him but he didn’t believe me but i blocked him and once again I told him if he kept calling or showed up to my house I would call the police on him for harassment.

My baby is 5 months old now and I keep thinking about telling him about her, I feel this guilt that because of me she has no dad and I don’t want her to feel like her dad didn’t want her because it will only make me feel more guilty for telling him the baby wasn’t his…

Should I tell my ex about the baby? Is it too late? Idk what to do I keep dreaming of him and i feel like it’s a sign that I need to tell him.

If you read this thank you and sorry for the long read