Ending a Relationship Forum - Should This Be the Last Straw?

In my current relationship, we've been together a little over a year, he lived about 1000 miles away with his parents since he graduated last year, and I was still in college. He drove all the way here to visit me for the summer and he's been living with me in my apartment for the past two months. And....he has a gambling problem. He thinks that after he plays enough, he'll be able to "make it big" and that online poker can be his career. He borrowed probably around $10,000 last year from me and his other friends to play poker...in the end his parents had to pay us all back cause he lost it all. These past few months, he used my credit card and took money out of my bank without permission, adding up to a total of probably around $9,000 (including charges my bank gave me because he overdrew $1000).

The couple months we've been living together he's been smoking lots of cigarettes, smoking lots of weed with our friends, "borrowing" money from me so that he can pay for these habits, and just basically sitting on his ass playing poker and video games all day. (I play video games also, but he plays like it's all there is to life)

After we've been talking about this the past few weeks, he's admitted to his gambling problem, and that he's going back home to live with his parents and they're making him find a full-time job to pay me back all the money. He says he promises he'll pay me back every cent. I thought this was a very good turnaround. He wanted to get his life on track and make a good life for both of us.

Lately he's been irritated easily. He gets mad easily, frustrated, and overreacts. For example, today (probably the worst overreaction I've seen from him) he was playing an online video game and he wanted to get food somewhere. I looked up the number for him in the yellowbook so that he could call it. He ended up dying in the game/getting his teammates mad at him because he wasn't paying attention to the game. He kinda flipped out and yelled at me about why I couldn't call and order food for him cause he was busy. I told him I was writing a long e-mail to my dad, and he was just playing a video game. He proceeded to get incredibly angry saying how he was sick of putting up with my crap, and he got his suitcase and packed up all his things. He couldn't find his cellphone, so he grabbed mine and started using it. I asked for it back and he wouldn't give it back so I tried to grab it. He pushed me hard down to the floor and said "yeah, go ahead and start crying, as if it's all my fault". (he denies it ever happened like this)

I don't want to go into too many details...but I feel like this should be the last straw, but I can't seem to let go. I still hope that he'll come back in a few hours and apologize and everything will be okay. Did I do something wrong to make him act out in the way that he did? I know he's been upset at me lately because he hates being nagged and I've been asking him how he's going to pay for the $9000 he owes me. Maybe I just asked for too much? I don't know, I'm really confused. I love him, and I feel that when I decided to be in this relationship with him, I was also saying that I would be there for him, have faith and believe in him, and help him through the hard times (and vice versa, of course).