It think it should be fine. Teaching a person how to drive a car is a life or death issue, which is even intense between unattached people, let alone people who have intimate relationships, like couples. Conflicts will be escalated and magnified.
Learning English from each other is a different story as long as you guys have a good attitude. You should have joked about your wife's "thinked" mistake instead of thumping your beer glass on the table. Come on, it's not a big deal, just a tongue slip. Take it easy, making fun of each other with kindness. If you can poke/ridicule/compliment each other for fun in English on daily basis, your English is bound to succeed eventually. You know only intimate people can achieve that, so make full use of it. :D
