This is the thing, he always supported me in everything I've ever wanted to do. He knew my insecurities and always said 'you should only ever change for you and nobody else' and that if I was unhappy then he would support me however much he could in terms of weightloss. Also, I have suffered with my mental health over the last few years and whilst he was always there to talk to, he also encouraged me to speak to others such as women aid in regards to the abusive side of my past relationship and my GP so it was never about only him being there for me.
You know, everyone has a little good and a little bad in them. He supported you, yes, but he also wasted 12 years of your life and cheated on his partner for the majority of that time.
It is blatantly obvious to everyone that he was manipulative which soils any bit of support he offered because it is fake and designed to make you rely on him.
To be clear, he may have been saying go get help from other sources, but he also made sure he contacted you regularly enough, asking you to lean on his shoulders, made declarations of love and support, and even when you blocked him he reminded you that he has always been there for you. He said get help from a professional but he didn't give you space to go to anyone else because he was always the first one there, all-encompassing, making sure you leaned wholly on him. That is a form of control.
His words and his actions don't match.
But, even if he was good to you, can you get to a point where you say, he was good to me in this season of my life and I'm grateful I had his support when I needed it, but in this next season I want to be someone's first choice and not their backup?
You cannot erase the past 12 years, nor should you as he did help you during that time.
But you must see clearly that the bad he did (make you dependent on him, prevent you from finding a real partner by stringing you along for years that you will not get back, not leaving his current convenient life although he declares he loves you, all whilst emotionally and physically cheating on his partner which tells you his true character) outweighs the little emotional crutch he provided at a time when you needed it.
He was good for a bit but now he's unhealthy for you. He could have broken up with his partner as soon as he saw how serious you were about ending things, but he still hasn't. She is his first choice, he still hasn't chosen you. Enough of being pushed around. Take control and draw a line under it. He was good in some ways, bad in others, but now you're starting a new chapter and it will be the best one yet. You are worthy and you can have someone who makes you their actual priority- proud to show you off, not sneaking around with you.