I just discovered my wife's secret credit debit

We've been together for 20 years and married for 15. We're a great couple, the kind our friends think of as "couple goals". We rarely fight and when we do it's normally over something trivial. And almost never about money.

We tend to be frugal and usually discuss things before making any large purchases. I became disabled about a decade ago and she's been the "bread-winner" of the family. She works hard and I'm proud of her. With the sudden contraction in income we had to file bankruptcy about 7 yrs ago and we've been good about staying out of debt since.

I handle the finances of the house, which really just means I file our taxes and check our bank statements. Yesterday, I was trying to reconcile our bank statement and trying to build a budget using our banks new software. This required me to categorize these transactions, which is a pain when a lot of them just say Amazon or PayPal. So I go digging into this only to discover she has two PayPal accounts and one is carrying $2500 in debt! We're not well-off people and that's a lot of money.

I was heart-broken. It was like my soul was just sucked out of my body. I felt something between anger and disappointment. I couldn't believe it. She must have noticed my sudden shock and saw what I was looking at because she began to reassure me that she's about to pay $600 towards it. I didn't reply. I went for a long walk to clear my head.

We still haven't spoken about it yet. I don't know what to do. I'm not mad anymore but I'm so deflated. We were supposed to be partners in all things. We don't even buy each other gifts without conferring usually it's just a joint anniversary gift.

To make matters worse, I can understand how she'd do it. She's got impulse control problems because of her untreated ADHD. She tends to self-medicate with alcohol to unwind and likes "retail-therapy" for self-soothing. She also has rejection sensitivity and is aggressively defensive. So even asking her about this may cause an involuntary lashing-out. But I must. I just don't want to.