Just found out my partner has been relapsing and not telling me

We’ve been together for 6 years. I’ve caught him lying about it at least 4 times now. The most recent was a few days ago. He swears to get help this time and has found a therapist. But I’m skeptical. I feel unwanted, unworthy, and like I’m not enough. My heart is broken. We’re supposed to be planning our wedding and now idk. I’m so hurt. Does it ever get better?