a. We dont know who bought what - YET. b. I am willing to take ownership of the chioces of what i bought if you are. c. I will not accept impromptu fiancial history or be attacked by it d. I will accept facts - you go find them
And if he keeps attacking you get up and excuse yourself
It's important that your conversation with him is calm... so when HE attacks he will learn you will walk away... condition him to either stay calm and stick to the facts or the convo is over...
Each time stick to that... if he starts blaming you steer it to facts or back to the conversation you WERE having if he tries to change it... DOnt' yell, don't attack, invite him to take ownership and wait