Hi Hanna and welcome.
Well done on looking for help.
I am sure you ahve been reading many stories similar to your own on the other threads here. You will also have beren reading the success stories – what are they doing that you could apply to your own situation?
As you say, your husband has every right to be upset and probably has little reason to believe what you say. This is where the old saying “actions speak louder than words” comes in. The actions that will help you stop gambling, such as posting here, self exclusion, accountability, maybe getting to GA meetings, using other support etc etc are the same actions that might give your husband cause to think “Hey, maybe she means it this time.”
Keep posting and let us know what positive actions you are taking.