This being so (wish I could say that in Latin)...
We once had a pompous Flt Cdr who loved using quasi-legal Latin terms in his letters, such as 'inter alia' ... An utter oik who thought his position in life was rather higher than in fact it really was. Courtney, you might have come across him when he was known as 'Thrombo' (the wandering clot) or 'AWF' (avocado with feet) in the early days of South Atlantic F-4 ops.
This was too good to resist, so many a made up Latin term was soon used in response to his turgid memos and minute sheets....
2 which I used were recalled from prep school days wrestling with
Kennedy's Latin Primer:
'Ob has causas' - meaning 'because of these things', but pronounced with Molesworthian glee as 'Ob harse cow's arse'...
'His verbis dictis, autem' - meaning 'these things having been said, however' - which is pretty close to your 'this being so', mike-wsm!
Ipso facto more correctly refers to the direct consequences of
actual fact rather than to something someone might have opined* as in 'His verbis dictis, autem'...
* - another wanqueword of early 1980s staff officer speak!