There's literally no point in this OP. People on here do not get therapy or attachment issues or understand how it works. You see it over and over, people thinking attachment to your therapist is a bad thing. It isn't. It's the whole fucking point.
You're supposed to attach to them, you're supposed to form a solid long term relationship with them, you can't do the work without it.
24 sessions a year apart is fuck all for attachment work. Might work for a bit of CBT work for anxiety which is what some on here class as 'mental health.' ACTUAL therapy takes longer and is much more dependant on the relationship. The whole point is in learning to attach, to trust that they will be there.
God I took 2 years to even get to a point where I could START working on the trauma. I didn't trust him, thought he would get fed up and drop me if he found out just how fucked up my head was. He didn't. This brings me to my next point.
It is absolutely normal to test your therapist. I tested the hell out of mine. I pushed him away, lashed out at him (verbally), accused him of not caring, baited him into more arguments than I can even count. (Downside of long term therapy, you learn how to push each others buttons) Occasionally I still catch myself testing him. Unfortunately yours failed. That hurts. Of course you feel confused and upset.
I do wonder if your therapist discovered a conflict of interest in treating you and obviously couldn't tell you due to confidentiality. Or possibly he just isn't a skilled enough therapist to work with transference and attachment. If that's the case he should have told you straight. But if he's not well educated or experienced enough to work with you like this then it's hardly surprising that he screwed up the ending.
You will find someone else who is more suited to working with you. Its important to find a therapist who clicks with and gets you.
My current therapist is the third I've worked with. The first wasn't experienced enough in a similar way to what's happened with yours. Second was just not a good fit. It was third time lucky. He didn't have years of experience or impressive qualifications but he learnt from his mistakes and went out of his way to educate himself further when he felt out of his depth. Grew with me in a sense.
Find someone like that who you can have a proper fight with, be completely unreasonable and know for sure they're still going to be there next week. This one isn't quite up to snuff. You will find one who is, don't be afraid to test a few out. No point wasting your time and money flogging a dead horse.