What should I do?

My sons dad has not been in his life since 2017 and that was the last time that he had seen him in person and in 2017 i ended up leaving when he was just about to be 2the relationship with my sons dad was very toxic and abusive and the night that i left him he went to jail and has felony DV charges pending against him and to avoid going to jail he ran to mexico he now has an active warrant for his arrest and hes been in hiding in Mexico ever since, as the years passed and i got older i moved on im engaged i have had more children since, my sons dad will call me on social media from random accounts asking to talk to my son even though we have this still pending case my son has always asked about his dad and wanted to talk to him so if i was able to make it happen i wanted to, my sons dad has been very off and on in his life my son is 5 years old and hes only ever talked to his dad via video chat 6 times he will keep in contact for a few months and then just disappear and the last time he did it back in September i told my self that was it and i was not going to allow the in and out in my sons life anymore because he always gets so emotional and angry when his dad leaves and i have to do damage control and it just wasnt fair to my son anymore so we tried to move on from it ei got him into therapy so he has help to work through his emotions with his dad and he got really better but 3 days ago my sons bio grandfather reaches out to me and wants to talk to my son and i was shocked because he had never once done it before and i have asked through out the years if he ever wanted to video chat the answer was always no and i have sent pictures and stuff i really did anything to keep my sons dads part of the family in his life but i never go any type of effort back so i eventually stopped sending pictures i kinda gave up, his grandfather asked if he could video chat with my son and i said yes i was hesitant but if it meant my son would have some family other then me and my partner then i was willing to do it because my family is not in our life, the video chat went okay my son was kinda shy and i explained to him that this person is your grandpa and he seemed to enjoy the call alot... i was okay with it until i got a message asking me if i would be okay with a 3 way call with my sons father who i had not spoken to in months and i said i would have to think about it talk with my partner and my sons therapist and see if it would be a good idea because i personally didnt want my son to go through as he did last time because his dad has not been consistent ever, it was dropped and he said okay i understand and he asked if he could talk to my son again that night i said sure after dinner would be fine....5 mins into the call he brings up my sons dad and told my son that he really wants to talk to him he misses him i grabbed the phone and flipped out i told him that what he did was not okay and that it was a choice that i needed to make for my sons best interest and i didnt want him to be let down once again because his son cant be consistent i hung up and i have not talked to him since...but now my sons father is calling me and messaging me on all social media asking to talk to my son and i have no idea if i should go with my gut and say no because of the disappointment in the past or hold on hope like i have done every other time and hope that this time will be differant....my son is only 5 and i know hes little but i dont want him to hate me when he gets older but at the same token i dont want him to have to go through what hes gone through every time in the past....what do i do?