always involved with the police.

As much as I'd love for my baby's dad to be in our sons life when he's born, I just can't see that happening. He says he wants to be involved but he hasn't been to any scans, hasn't bought anything and avoids talking about the baby every time I bring him up. He uses excuses like "oh I'm tired now got to go". I can do it myself but my problem is that he is always involved with the police. For stealing, drugs, fighting. 
Luckily he got put on probation but he doesn't show up so they're thinking to give him 3 months. Now tonight, he's posting on Snapchat of him yet again, surrounded by police and filming it making a mockery and so on. I wanted to pop up and give him a piece of my mind but I left it. He wants to teach my son the ways of life and this and that etc but I'm scared? At one point as a joke, he said that our son will be just like him and said it was a joke so I left it but now I'm realising he is actually trash 😕 he was never like this!! Only after we split & I'm still willing to be his friend, maybe he might be a great father figure when the baby is here? Idk.... what should I do?