I can imagine it is heartbreaking for you. I’ve seen what it did to my ex. But she used the odd time aswell. But it’s all the lies and dishonesty that comes with addiction is horrible.
All I can suggest is to keep communicating with people in your situation and talk to family members. It really does help talking to someone. And maybe go out with friends to take your mind away from things. I know it’s easier said than done. But you deserve to be happy.