Divorce, new partner and blended family !!!

Hi All, I'm completely new to this group and new to any kind of advice forum tbh.  I'm a mum of 3 children aged 23, 20 and 15 (eldest and youngest diagnosed), I divorced some time ago and am now in my second relationship, we've been together 5 years (lived together 4) and plan to marry hopefully next year.  My eldest child has struggled throughout this big change and has never accepted my new partner and infact told me quite clearly that although he was happy that I was moving on and finally finding happiness he would never accept a new partner.  My son has lived at Uni for the past 3 years but whenever returns home for breaks etc. has never spoken my partners name, addressed him in any way, he leaves the room if my partner walks in and is generally unfriendly towards him. My partner has tried very hard to bond with my son.  He's driven every uni move and helped move him in, been his guarantor for uni accommodation for the last 3 years, he's lent him money when his student loan won't cover his rent, buys him random gifts if he sees something he thinks he may like (Star Wars fan), tries to make conversation with him but nothing has ever helped and it's seriously affected my partners mental health at times and he has needed anti-depressants prescribed by the doctor.   Recently it came to quite a head as my sons dislike of my new partner became unbearable for the whole house as the atmosphere affects us all so I sat him down and told him that he needs to be respectful as we all have to live in the same house, that night he refused to come down to dinner and left his meal on the table the entire night.  He made it very clear that he was not willing to act respectfully and I said that we cannot live this way.  He left home the next day and is now staying with his father and telling everyone I kicked him out.  He has since blocked me on all social media and refused and contact I have attempted to make with him.  It's now been 2 months and no progress at all, I'm at my wits end and feel I could be heading towards depression.  It's made me feel like the last 23 years I devoted to my son has been for nothing.  It's been a long hard road and I gave everything and feel I'm now being treated so unfairly.   I would appreciate any advice/help if you have been in a similar situation, thank you