Tough love with adult child part 2

He is out of the house almost 3 weeks, he still choses to make a point and live in his car, he told us several times when we said we were going to downsize that he would. He works for me and two days ago he came into the office, did not speak with me but left his finished work on my desk and I was with a client and said thank you, no reaponse. he came into the office yesterday but I had just walked out and my secretary spoke with him briefly. To give you more background, he is insecure because he looks 17 and he is 26, something to be thankful for later I would tell him, he believes her can hear what you are thinking, a month ago he was trying to force me to fire an employee that he felt didnt "like" him, I refused and told him that u have to learn to work with all pppl in the workforce. He is not talking with anyone in the family but my brother. I have texteed him twice with the offer to pay for therapy andhe texts back immature comments, my last text iwrote that I will not engage in immature sparring and he will not hear from me again that i am only trying to help and I love you,
My question is: How do I open the lines of communication without letting him think that he can move back in my home, (i am done with that). Should I wait until he tries? His drug problem needs to be solved (marijuana) but he does not think its a problem and his hate (or jealousy) for all of us needs to be resolved. Do I invite him to dinner, outside of the house? Or again let him come to me when he's ready to deal with all I have told him? Rem. it's tough love, I can be really tough just need to know what is best for all of us. He has gone to counseling before and would tell them what they wanted to hear and it did not help. I know he has to want this bad in order to change his life he is very stubborn and right 150% of the time. We kicked him out 2.5 yrs ago and he was back iin 6 wks, wrong thing to do, as we have 20 20 hindsight. I also don't know if I am ready to talk with him, I am very hurt by his words and actions. He has been verbally abusive to all of us.

PART 3

thank you to all that commented it has been 5.5 weeks since he left, in the mean time we had an interventionist come and my son agreed to get help they left for CA and on the drive after 11 hours in flight, decided not to go, he is back here, now I hear that he is looking for a place, he quit his job ( with me) and I feel that a weight has been lifted from me everywhere, I believe when he is ready, maybe never, to give up pot then his life will be full of joy, but until that time he has no family.  That was his choice, I love him but do not like the person he is at this time.  ONLY YOU CAN CHANGE YOU