I'm very sorry to read all this. I thought that we hadn't seen you on the forum for a while, so assumed that you were busy with your studies.
If you have the phone number of this person and evidence of hacking, then you could simply pass all the details you have to the police. However, the man who did this may well know your address, if he has your phone number. Please be careful. You don't want to make this man angry and risk worse happening.
It sounds to me, judging by the details you have given, that this person knows you personally. I'm not very familiar with Google Plus but I seem to recall that a mobile number is required for part of the process. If this person knows you, he may have been able to guess your password. Do not use anything which someone else could guess (e.g. name of a relative or pet). I would suggest making your password as abstract and as long as possible, with random characters and numbers included.
This is worrying and please keep us updated. I hope that this will not distract you too much from your studies.
I recommend that you seek the advice of your parents about what to do. Also, I suggest that you make sure that your mobile network is aware of the problem and monitors usage of the number.
My best wishes to you at this difficult time!