My DH used to say "I" and "mine" all the time.  Like you, it always irritated me immensely.  Everything we had was "Dad's".  I have always a career and am now retired; therefore, I had always contributed to our joint earnings and property acquired (38 years).  Our divorces devastated us financially and we had to begin all over.  We now have a beautiful home, nice vehicles, and a comfortable life.  We earned all this together for our retirement.   

I finally told DH, one day, I didn't want to hear it again!  Every time he said it, I reminded him, when we were back home or alone.  Now he says "we" and "ours".  It took my disengagement from SD57, her reactions to my disengagement, my staying quiet with response to SD, and DH finally witnessed her true colors.  DH visits with his grown children, but I am disengaged and am civil and tolerate; but I opened DH's eyes. 

I suggest talking with your DH about it, in privacy.  Every time he does it, remind him to listen to himself, when he is carrying on a conversation.  I also took the opportunity to correct his wording, if it was not embarrassing to myself, when he did it.   

You can correct this, without a good deal of drama.  Just do it each time it happens.   I posted here July 2016 about this very same irritation. 

ROM:  This is my post from July 2016: 

Reading here, I know this is not uncommon, but it bugs me; although I am disengaged from SD56 and SGD31 (mother/daughter). Being disengaged from these two women, I've always been civil and never had words with anyone in DH's family and have for 36 years been included in any gift giving by DH. I keep my disengagement separate from DH's family members, that treat me well. Any gift giving to anyone that I do, DH is always included; especially my family. DH does all the gift giving to his family.

SGD31 sent a thank you note addressed to "Grandpa (DH)" only. SGD31 lives in a neighboring State and mailed it to DH. This didn't surprise me, due to the fact that SD56 and SGD31 are furious, because I have taken myself away from their drama. The envelope and note was hand written in SGD31's hand writing, suppose to be from SGGD13, another phony move.

DH and I had given $$$ to SGGD13, who is on a softball team; they were recruiting donations for new uniforms, last Fall (9 months ago). Included in the Thank You card were pictures, which I updated existing frames that are displayed.

This was a passive aggressive move on SGD31's part and I know the game she is playing, therefore, no response to her from me. She even wrote in the noted "Miss you so much Grandpa"; because SGD and SD think I am the cause DH never spends time with them. Now if you've read my previous posts, you know any contact with these women is on DH and them, I'm out of the picture and have been for 7 years. I have never told DH who he can visit and who to associate with, thus he is also considerate with my family and friends.

Bottom line, after receiving the Thank You card, I had a talk with DH. I told him I am tired of these head games continuing and I want him to set one thing straight; which DH has not done in 15 years, since SD moved here. I ask DH to use the word "We" instead of "I" from now on, concerning any Skids or Sgrandkids. I don't have to be called "Grandma" or be included in any family gatherings, that I don't want to attend. All I ask is that DH treat me like his spouse and show SD and SGD that DH and I are a team; especially when it comes to giving donations to the Gkids. He agreed that he would be more mindful.

I do not believe I'm being too snarky about the words "We" and "I". I noted to DH that never have I used the word "I" to my family or friends, when referring to us. I've always included DH and I always use the word "We", especially to DH's family and kids. DH has always been included in my conversations and actions.

I know this is the bottom root of our problems in the past year; SD and SGD are trying to single DH out away from me. I told DH as much and he seems to understand; we'll see how he handles it from here.

I read here and believe that disengagement can be civil and that a couple should be recognized as a couple. There is nothing to gain by these women, SD56 and SGD31 playing these games; except to be rude to me, I understand that part.

Yes, been there.

A counselor told him not to setup our relationship to SD as if I don't exist. He tried for a while. I think in all these years, he only asked me to sign cards to her twice. I demanded that when she asks him to borrow our car or to visit that he say, "I'll have to check with Marblefawn," but it was always a battle to get even that much consideration.

When I disengaged (the final straw was a postcard SD sent to our house addressed only to him) he reverted to acting as if I don't exist again. That's how it's going to be so I act as if she doesn't exist. She is not welcome in our house and I never ask about her, even after he's spent a weekend with her. It's petty and unnatural, but it's the only defense I could think of.

In my mind, it stems from my husband wanting to downplay the fact that I exist because SD doesn't like him having a wife. He does not talk about her to me, so I guess that makes us even. Sad that he didn't rise to the occasion to try to bring us together. Maybe his next wife will have more luck.

I would start immediately correcting him regardless of the situation at hand.  "Ours not just yours!", "Ours!", "Yet again... Ours!"

I have had to do the same with my bride over the years. Interestingly... once SS-25 asked me to adopt him three years ago... DW seemed to resolve this issue for herself and I have not had to correct her nearly as often as was the case when SS was  young.  Really the only thing we had this issue on was the Skid.  Everything else... was "ours" and "We" pretty much all of the time.  We met when SS-25 was 15mos old and married the week before he turned 2yo.  I called him "mine" and "ours" from the beginning.  It took her a few  years to shift from "my son" to "our son" and never quite got completely past it until the adoption.