You wrote: “What I’m really struggling with is handling the situation with my girlfriend.”
Put yourself in her shoes … you said, “I’ll always know I should have an extra $150k if it wasn’t for my stupid gambling. And that’s a ton of money, it’s ridiculous.”
She knows it too – and it is affecting her life as well. Yes she is mad / sad / depressed and probably needs to vent at the moment. Once she has done this – you both need to look rationally at the situation and plan for when you will have money again and be dealing with the urge to gamble. Have you put barriers in place? Ensure that you are banned or blocked from places where you might gamble – all of them. Can she handle your finances for a time until you are strong enough to take back control, (and this might take years?) Are you getting support from as many agencies as possible, not just here but in your local area through counseling or Gamblers’ Anonymous or similar? Have you a plan for how you will use your time?
Gambling is something that we do alone. We hide it from our loved ones because of the shame we feel. The opposite needs to happen with recovery, to be open as as involved as the others want to be. Some partner’s see it as something a couple / family should deal with together. Some see it as something the gambler needs to deal with, albeit with their loving support.
At some point when the mad/sad/depressed phase has run its course – have a conversation with your girlfriend about how she can support you and how you can support her to get through the next few years without gambling together. I wish you well.