got pregnant from a vanilla one night thing (not LS partner) how do i process

ok so context, were ENM not strictly swing, hubby and i have a slow occasional "outside" arrangement where i sometimes see solo guys (with his knowledge + boundaries). met a lovely vanilla guy at a work thing 6 weeks ago, one night, used protection but apparently not well enough. positive test 2 days ago. early early days. hubby has been incredible, said "we'll figure it out, together" which made me ugly cry. but my brain is a hurricane... the guy doesnt know we're ENM, doesnt know about hubby, just thinks i was a single hookup. do i tell him?? do i keep it?? what does coparenting look like across vanilla/LS lines... someone please be honest with me