Line manager resents my promotion.

I have been a manager for around a year now, I am in an industry I have 15 years experience in, and recently went from a team leader/supervisor role to a full on manager.

I work closely with my line manager, who is nice enough, but isn't amazing at his job, but he does try, I have always done exactly what he has asked and picked up his slack to ensure that our sector runs smoothly and that he isn't dropped in it for the mistakes he makes.

Recently our director asked me to apply for an internal role away from my sector, I spoke to my manager about it and he whole heartedly supported me going for it, so I did, the interview went well and I had to discuss situations I had dealt with that related to their questions (what would you do in this situation, tell us examples etc).

A few weeks later I got a call saying that I unfortunately didn't get the role, but they wanted to promote me due to the fact that I have been clearly doing work above my paygrade, I naturally jumped at the chance and I am now basically now in a junior/assistant role to my manager, being one drop down the ladder from him, rather than several - and he is not happy about it.

He kicked up a stink straight away that he hadn't been asked or informed and that our director had gone over his head (even though the director is way above both of us in the business) and that he will now be struggling as my previous role won't be filled, even though I explained my job role won't be changing, I have just been promoted to reflect the work and workload I have been doing, he just cannot understand it.

He now makes digs when I get a congratulations, talking about how it was a consolation prize, he sarcastically asks me if something is below my pay grade when I say I am carrying out tasks I have always done and most recently - and probably hurtful - one of my supervisors mentioned he had been heard in the break room talking to other managers that he didn't understand why I got the promotion when there are others just as deserving, basically stirring up resentment amongst my colleagues who were on the same level as me in different areas.

I am beginning to resent going to work and feeling like working hard, supporting him and being proud of my promotion is something bad, when I feel as though he should be championing me, how can I deal with this in a way that doesn't involve me going to our director? Is this just a case of he thinks I am biting his tailcoat and he is worried that soon people will realise that the company could function exactly the same without him? Or is it more that he genuinely thinks I am not deserving?