Let me see if I can help. I want to be supportive to you, but I also want to be realistic and honest as well.
Your previous boyfriend has very complex and multiple issues. He is bipolar. He has a neurologically based issue, dyspraxia; he drinks; he can be callous and abrupt. In truth, this relationship, if you decide to pursue it further, will be challenging.
I am concerned for you as I feel that some of what you have written could simply be his own personal struggles and difficulties. Other parts, the more serious behaviors, seem more personality based...and the impulsiveness that he seems to be experiencing more and more of is an indicator, as the doctor stated, of a possible impeding hypomanic/manic episode.
He also showed little concern for your "relationship test", where you portrayed another woman on-line and asked about sex, to which he replied that he wanted to...book a room. Then when confronted he says he is just punishing you and he would not do so. That makes no sense. A man who loves you would not act like this, intent not. This entire situation seems very unbalanced and all about him. I am concerned that if this progresses, his whole interaction will become about him and your needs will be not addressed at all.
Best practice in these cases:
If he wants you he needs to show some behavioral changes. He should agree to steady and consistent treatment of his bipolar disorder. This is a genetic illness and responds only to consistent treatment. Going on and off again when he feels better (or when he feels the drugs are blunting him) is an ineffective method, and he will not enjoy stable moods as a result and his behavior could be damaging to him, and to you.
He must agree to no drinking. His conditions worsen with alcohol and he must invest in a plan where he is abstinent. Some folks just cannot drink because of medical conditions. He is one of them and must show that he loves you through actions like this.
Lastly, he needs to show you respect. To tell you that you no longer excite him is hurtful and the exact opposite of love and care. To me, he is hurting and lots of that hurt is being directed at you. He also needs to invest in his recovery and needs to see that he must be serious about his illness, lest he lose you and even worse.
I would suggest putting this relationship on hold for a little while, just to see if he can show maturity and investment in you. You are worth more than what he is offering you right now. He can change if he wishes; he is not hopeless by means, but he must make that choice, and you can assist him in wellness by making that (done in love) demand. Steven