I think giving you ideas on how to handle this is not the best of ideas, as it’s enabling you and possibly making you stay in a situation longer than you would. (Similar to some women who say ‘he hits me, but is great at other times, how do I get him to stop/learn to live with being hit, so I can stay for the children?’. When everyone removed from the situation can see the only thing the person should do is get out).
But assuming you know your own life, and know best, I would have a chat with DH and say you’ve going to stop taking on the mental load of worrying about $, and in order to do so, the best way forward for you both is to have one joint Bills account, into which you both have an auto transfer of you total yearly bills divided by month and split in salary proportion.
Then you have a second account called House, which is 1-2% of your houses value, again divided by the month. Again you both put in an auto transfer every month from your salaries, in proportion. (As an aside, 1-2% is minimum what is recommended people spend on home upkeep each year. So this is for emergency household work when the boiler/oven breaks, the plumber needs to be called or, hopefully, you planning ahead and using it to replace the oven/washing machine/roof when you know it’s getting old etc).
Then you have a third account called Holidays - same as above. You can’t take a holiday until you have money in the account to pay for it.
After than, all your money is your own, in your own personal accounts. You can save and he can spend, it’s your own choice. But the three accounts above are not to be touched except for those things. Make them hard to access the money if you too, as the second and third should only be accessed for long planned purchases anyway.
Personally, I would say you need an Emergency Fund of 3 months expenses first, and forgo the holiday fund (or pay more from your own portions) to fund this. But I suspect your DH will not respect that account and see it as one to ‘raid’ when he wants something. So I’d do the above and probably save on my own, knowing that my own savings won’t be used for emergency big bills anymore.
Finally, you have to stay chill, and enforce it. So there isn’t enough money in the holiday account for a holiday DP wants? Then you don’t raid another account, you go on a smaller holiday (or no holiday) and save up for next year. If DP buys iPads or smart watches from his own account, fine. If he raids one of the accounts, you insist he repay the money immediately. If he goes into his overdraft to do so, it is NOT YOUR PROBLEM TO FIX. You have detached. You are chill. The main accounts are secure, everything else is his problem.
In a perfect world, I’d also suggest 6 month Emergency Fund account, offset against your mortgage, and money into your pensions. But that’s something you can work towards. I think it will be v hard to do the above as it is.