He's got the money, when we were living together I trusted him with it and it looks like that's what he's doing.
I'm really sorry, but am I understanding this correctly? You were going to buy a house together, but the sale fell through so now you are living with your parents, and he says he will take the money and buy a house for himself.
Once you have proved yourself to be reliable for six months 
, then you will be allowed to live in this house that he has put half your money towards (and at some undefined point in the future, you might get a house if you 'prove' yourself, and if you don't, will he give you the money back, or just deny he ever took it). At the same time, he is going off on holidays with his mates, which you are not invited on, over your birthday.
Does he already have your money in his bank account, or is it in a joint account or do you still have the money in your own account? I really hope that you still have it. If you don't, you need to ask for it back. You can't accept a situation where YOUR money goes into a property not in your name on a promise. What evidence do you have that you gave him this money and why? If he has it, you can ask for it back and say you have found a high interest account to put it in, until you find a joint place. A joint place was the condition you offered/gave it on, and that should be the way forward.
If I am right, and he has the money, is putting these conditions on things, and is going on holiday without you, then I think your anxiety is a perfectly normal response.
It does not matter how many MCs he has been through - this is NOT a normal and kind response to a partner who has been through six herself physically and emotionally. I had three, and the emotional and physical toll is huge, never mind all the stress of house purchase falling through. A loving relationship is about support.
How supportive are your parents? Have you been able to talk about this with them? You do need to talk to your GP and see what RL support you can get.
Five years of your life you have loved and trusted your partner, so you obviously don't want to think badly of him, but however you look at it, suggesting that he take the money and buy himself a property is not the action of a person who really deserves your love. I suspect in your heart you know this, which has triggered the anxiety and disordered thoughts. I suspect that you also know that looking at people's medical records is deeply wrong and that he may have told you this as a means of control and blackmail so you will feel limited in seeking any treatments you need. It is a gross violation of privacy, and awful to even give you that fear.
The priority here is your health. You need to be healthy to make any decisions or to deal with the situation. You should not be making life decisions when you are mired in anxiety. Please, please look after yourself, and find the advice and support you need beyond your partner so that you can recover.