How & when to tell him I’m pregnant ?

So I’ve been seeing a guy for 3 weeks now,

And it may sound cliche and crazy considering the time length but I’ve never felt this way about a guy before. Even when I’m talking about him to friends Apparently I’m super giggly and smiley so it’s pretty obvious how I feel... he’s just so affectionate I was definitely not used to it, especially in past relationships were I was called disrespectful names etc..

but we’ve been sleeping together as well... the first time I even brought a condom and we used it and everything... but the second time although I brought another one we were up in his room and things were getting intense... so basically we started having unprotected sex (I know 😭) he asked were he could come and in the moment I told him to cum in me (I know) but I asked him were he wanted to and he just came in me.... and ever since then that’s been going on. I’ve been on the bc pill but I know I don’t take it regularly... I forgot a lot. And I’ve been meaning to get an iud since this pandemic started but I haven’t been able to make an appointment yet. Soo I’m pretty terrified to tell him because I think he will blame me and he will be upset ... I should have been more responsible with taking my pill as I’m already a single mom to 18 month old twins so I feel like absolute shit. Please don’t judge I already know I messed up big time. Any advice ?