Bun in the oven and dating

Bun in the oven and dating Advice sort: prior to my partner and I being together (now going on 9 years) we had both had experience with open relationships but ours has been mostly monogomish, particularly so since Covid. Last night Partner let me know that he’s started chatting to someone they’re interested in- which was a surprise to me since we hadn’t had a conversation about non monogamous dating in about a year. I’m 6 months pregnant, with an another under 2, and have had a hard pregnancy due to poor health. Struggling with the idea of introducing dating others right now when it’s not something we’ve done before in our relationship and we’ll have a newborn in the midst soon. Anyone else with experience of dating new people while either yourself or partner is pregnant?? (FYI I did encourage him to seek someone out when we first discussed it- but the timing of him landing this in my lap right now out of the blue is feeling like a lot!)