Everything falling apart

I need some positive thoughts and encouragement. I am sorry for the long post. My husband just left our home fuming with anger. We have been married for 15 years and for the most part he has been my SOLEmate. It was US against the world and nothing was to hard to accomplish. Both of us are immigrants from poor countries and were are able to accomplish MY post graduate doctorate and somewhat stable financial situation (couldn't do anything without his love and support). When I was done with schooling I had horrible baby fever and convinced him to have a child. He relenctantly agreed. I continued working on my enhancement, I got amazing job, and i was able to build my career really quickly. I also got pregnant easy and i enjoyed my pregnancy. Life was good! Unfortunately my husband started sinking into depression and started self-medicating with first light drugs and then heroin. I was so immersed into my goals that i haven't noticed much, untill copious amounts of money started to disappear. Our life was never the same and last 3 years were just plain hell. Everything I have tried to do just further pushed him away and we couldn't avoid sinking deeper and deeper into despair. His drug use was uncontrollable. He became abusive, mostly nonphisically, lied to me continuously and had no regard for anything but doing drugs. Has left our home multiple times, promised change but turned around and just continued his reckless ways. Has done rehab, has gotten clean many times ( but it never lasted long) and has tried long term opioid antagonist but it didnt last. He strongly believes he is beyond help and there is no hope. When he is clean and follows what ever agreement we had at that time, he is back at being MY husband that I loved and admired for 3rd of my life. But it never lasts and he is back to using. Last May we had amazing 45 days of our life. He was clean, back at being my husband and he had a job

Things have been returning to normal, life was good but unfortunately we managed to get me pregnant accidentally. He did everything in his power to convince me to terminate pregnancy, which was out of the question for me. Since then everything fell apart. He left us with majority of our savings and indulged in careless drug use. Lost his job and become homeless. That lasted 40 days. Our families convinced me to accept him back into our house as they were oblivious to his addiction. I have never shared that with them as they do know drug use only through TV screen. Things were hard when he returned as he continued his "drug use and getting clean" cycle for next 6 months. We have been sleeping in separate rooms for some time now. I have my parents ( both retired) with us to watch our baby while i am at work as i could never trust him enough to live him with our son. Our son loves his dad even though he is rarely doing anything for him or does any major caring for him. So my question to you ladies is would you let him go and cut all ties with him or continue this struggle. I feel conflicted and confused and I still miss the idea of the life we could have had if there were no drugs involved. What should I do that would be best for our children? I still love him dearly but i cannot watch his self-destruction and him destroying us financially. Please help me