I was in a 4 year relationship with a meth addict. Meth is one of the nastiest, most evil drugs on the planet.
From what you have said it definately sounds like he is using meth. It will only get worse. My ex was a pretty sweet loving guy by nature, and very gentle, but when he started using meth [behind my back, it went on for 2 years before I found out about it] he became more and more abusive. The things I went through with this man nearly killed me..he was mildly physically abusive at times but it was the horrible, unbelievably evil, mentally abusive, manipulative nature that meth gave him that really caused me the most pain.
Theres a lot more I can say about my story and I will if you are interested. But I warn you...this situation is not likely to get better without him getting help. Have you talked to him about his addiction?