Anxiety about telling my partner we have a surprise pregnancy

So I am pretty sure that I have tested positive and I'm waiting on a doctor's confirmation this week. I've been feeling a few early symptoms, but wrote it off as a heightened form of my normal PMS. And now I'm having extreme anxiety about how to break the news to my partner. This comes in part from the fact that my ex-husband who I share two kids (one angel baby) with used to flip out on me when I shared about becoming pregnant. Then when my current partner and I got pregnant with my daughter it was an IUD fail and he had a really hard time adjusting to that news because he wasn't ready at that time to have a baby.Overall, once he accepted it it went smoothly and he absolutely loves our daughter.

However, We recently sat down and had a discussion about what the future looks like and decided that both of us were done having kids because

A. they are expensive

B. I'm currently a stay-at-home mom working on getting back into a career field once our daughter goes to kindergarten

C. covid has created a number of uncertainties in the world and he's been the main provider since I lost my job and childcare at the beginning of the pandemic which has created some financial challenges.

He also has a very strained relationship with my son from my previous marriage who lives with us full-time (who is nine) as he has severe ADHD and has a hard time with impulse control and boundaries (but is in behavioral therapy). My son's behavior also seriously stresses me out, but it is different since I am his bio mom. They try really hard to connect and get along, but there's just some kind of wall that seems to exist there that has been really hard to get past.

Lastly I had covid really bad last year and my health has not been the best since and I'm at the heaviest I've been in over a decade, So all of these factors are adding in to my massive anxiety and feelings that I have no idea how to move forward. I don't think he would be angry per se, but I think it would add a level of stress to the stress that we're already dealing with that I'm not prepared to navigate. I wish I could feel super excited about this, but my emotions are so mixed based on these other factors that I don't even really honestly know how to bring up the conversation. This is entirely on me and not my partner because I have a tendency for people pleasing and conflict avoidance that I've worked really hard to do better with (was married to a domestic abuser for over 5 years).

Anyhow I just need a safe space to vent this and to get input.