Thank you for sharing @jfh and welcome! I understand the struggle. My boyfriend has been battling heroin/opiate addiction for over 10 years and it’s really difficult to see someone you love turn into a completely different person. It can be really draining and exhausting. For a while, I fell into a deep depression because I felt stuck and had no idea what to do, how to handle things, and what I can do to move forward. I started going to Al-Anon meetings and found myself a counselor because every time I tried talking to friends or family, they just didn’t understand and it made me feel even more isolated. I started following support groups for loved ones of addicts on every avenue I could find whether it was through social media or some other forum. It was so comforting for me to talk to other people who understood what I was going through. The support, reading their stories and similar experiences, and encouraging advice made me feel so much less alone.
One thing I found extremely helpful is to set boundaries and stick to them. My boyfriend can be extremely manipulative when he is actively using. The more I allow him to take advantage of my home, my money, etc., the more it enables him and continue actively using. One of the boundaries I set was if he is actively using and does not plan on getting help, then he cannot live with me. I always made sure to remind him that I love him but when it starts to negatively impact my mental health, I cannot allow him to be around me. This also ensures that you are taking care of yourself first and be the best support you can be when he is ready to get help, if you choose to stay in the relationship.
Just my two cents. I hope this helps. Good luck and there is hope, it can get better!