Name changed for this -
Have felt unable to talk about this with family and friends, any advice would be appreciated.
I have 1 DS under 1. His dad and I hadn't been dating very long when I got pregnant, I decided to continue with the pregnancy after speaking to him and him telling me he would be around for the baby and wanted to be with me etc (I would have kept the baby either way though)
As it got to the end of my pregnancy his dad did some really shitty things - updating his OLD profile - but denying he was using it. I checked again and he'd updated again so he blocked me from the site. Denied it completely and said he deleted his account (he didn't). This prompted me to get an STI test and he'd given me an STI - had only had sex with him in over a year and they checked at the start of my pregnancy for STIs so it was 100% him and something he'd obviously caught while sleeping around during my pregnancy.
only found out about it a few weeks before my due date - could have caused blindness or pneumonia in baby if it hadn't been found.
He completely denied it and said the tests aren't 100% (true but what are the chances). Had the test redone and it was positive again. And negative after taking the appropriate antibiotics. 
Since Ds has been born he's only met him a handful of times but makes it clear he wants to play a part in his life. So far he's contributed a grand total of £0. I've brought this up several times and he's avoided the question or changed the subject.
Feeling shit about all of this because I don't want to block him out of DS's life because they might have a great relationship in the future. But sick of having to be in contact with this man as it reminds me of the shitty selfish things he's done and never acknowledged. He can also be manipulative and try to use how I feel against me (doesn't work anymore)
He isn't on the birth certificate and I haven't contacted the child maintinence service yetbut I'm considering it.
Not sure what to do 