I think we have all been there at one point or another (I know I have!) when we've had a bit too much to drink and end up blowing all things out of proportion and having a huge row.
I find that if you have both had a bit too much to drink and feel like it is heading that way then just keep your gob shut! Easier said than done I know, but honestly bite your tongue and tell him (and him to you aswell) that you won't talk about whatever, ex's in your case, right now but if he wants to bring it up in the morning then you'll happily talk about it then. This has happened nurmerous times over the years with me and my hubby and now we don't row atall when tipsy, it's really not worth it. half the time neither of you have a point but are just being drunk and stupid.
At least if you if refuse to row after you have been drinking you can wake up in the knowledge that you haven't said something awful that you regret, that there is no awkward silence and if there is a genuine issue then you can discuss it whilst sobre as adults. Good luck x x