End of a relationship

I fucked up. My boyfriend of 3 years left me. I fly back to my hometown with my son, who is 3, tomorrow. He’s known him since he was 6 months old. We weren’t together everyday but when he was around, he loved up my son like he was his own. (He’s not his biological father). My son loved him too, he calls him daddy. He doesn’t see his bio dad, he’s never been around.

I just feel so bad & sad, that my son is clueless that today is his last day/night with his “daddy”. He said he’s going to talk to him, a proper good bye, I hope my son understands. I’m sorry my boy, mama was stupid & fucked up. ☹️