Hello, Maresme &

I'm so sorry for the stress and trauma you have been going through, and I hope that you and your son are safe--that is the first priority... .
I don't have any experience with a loved one with a meth addiction, but I do have an adult (38) son who used to have a Heroin addiction for a few years. He detoxed (though was still addicted), and then was admitted to a Dual Diagnosis Center where he was diagnosed with BPD, in 2013. They treated his mental health issues as his first problem, and his addiction problems as co-morbid. He has been clean and sober ever since (two years!), and is also in recovery for the BPD as well; he is the happiest and healthiest he has ever been... .
My son is still in treatment: Out-Patient Therapy once/week, Neurofeedback Therapy once/week (changing to twice/month now) and a Psychiatrist once/month. Though he is totally clean and sober, he needs the treatments and I don't see them ending any time soon... .I don't believe he would even be diagnosed with BPD at this time, though, so I know that recovery from that is possible, also.
Please get your boyfriend help; he cannot kick this addiction or solve his BPD problems on his own. There may be a Dual Diagnosis Center near you--my son had completed 2 different regular Rehabs in a 3-year period (the last one was a year before the Dual Diagnosis admittance), and neither of them addressed his mental health issues and he relapsed both times. The DDx Center was the only program that helped him in a real and sustainable way, and I highly recommend it for people with addictions combined with BPD or other mental health issues.
Please take care of yourself and your son, Maresme, and I hope your boyfriend can find the help he needs