Hi OP,
I completely understand where you are coming from, and I am a couple of decades ahead of you, but was in a similar position with my DD.
It is incredibly hard not to be emotional about it, you love your DS so much, it actually feels offensive that their other bio parent appears to have no feelings for them, it used to feel like an insult to me personally when I was in that situation. My DD's father had seen her a handful of times in her first year, but disappeared when she was a year old. No contact, no idea where he went..... for 18 years.
Then he reappeared out of the blue wanting to see her, really sorry, can't believe he'd done it, he always thought of her etc etc. It was an awful time for DD, and me and my DH (who had been with me since DD was 2).
DD met him (I was very open to him seeing her and encouraged her to meet him), she was obviously curious, and was probably hoping he would be a perfect dad now.
When things didn't go as he planned and DD found it very hard to build any kind of relationship with a complete stranger who knew nothing about her whole life, he didn't like it. DD was obviously old enough to see things as they really were, but it did take her months to feel able to cut contact with him for good when he still let her down and broke promises. She no longer sees him, and he again makes no effort with her. So as sad as it is, sometimes men really aren't bothered, and can switch off to the fact they fathered a child and abandoned them.
Sorry for long story, things may well be different for you and your DS as he is only a baby, but although I am sure you would facilitate contact if you have to, you may not have to. I'd keep a low profile and not contact him again, but be open to things if he does. You may just find he still can't be bothered even if he does get back in touch, it's hard work being a proper dad and he may not be up to it.
It turned out DD's dad had quickly married and taken on a step daughter a year younger than DD. So he preferred to help raise another child than see his own.... tough one for DD to deal with but she's doing well.