[exarady]

So I am a 20 year old man and just finished my first year of Dental medicine school. In my country (Romania, Europe) if during the year you fail exams you get the chance to take them again at the end of summer, beginning of September in my case. I failed a few exams, not ashemed to say that, dental school in our country is a bit harder than the US or other parts, mainly because we have to learn lots of general medicine. Ok now that that's out of the way, let's get to the issue at hand. At the beginning of summer I met a girl, a girl I would describe simply as a person which possesses all the qualities I looked for in the opposite sex and almost none of the defects... she is 24 years old... needless to say I fell pretty hard for her. During the weeks after we hooked up I gently started to let my parents hint that I might be seeing someone, (now I think it would have been better to just keep a lid on it) they didn't seem to mind at first. I kept studying in order to pass my failed exams... and occasionally made time to meet up with her. Two weeks ago she was gone with her parrents to another city at some relatives wedding, and we didn't see each other for about 10 days. When she came home.. she came alone and by train, so I went with my car to the station to pick her up, take her home and spend some time with her. Like always when we meet... time flies and around 5 things got sexual, and concluded with me getting home at 7:45 AM. When I arrieved my dad had just woken up and found me in the doorway... one of the worst fights I have ever had with him ensued, in which he pointed out in a verry vivid and vulgar way that he dissaproves of this kind of behaviour, that things are going too fast between me and my girlfriend, that I should stop seeing her, and that I have lost all interest in my school issues, he also seemed verry worried if I used protection or not, I explained that I did, knowing that he asks because he is afraid of how I could ruin my life if I leave a girl pregnant at this point, but that fear is unfounded because I suffer from delayed ejaculation, a condition I also can trace back to how strict he raised me.
After the fight him, my mom and my grandparents on his side organized a sort of intervention in which they all pointed out that they think she is too old for me, that she is probably starting to think about marriage (24 is not too early in my country) but the discussion was mostly focused on how determined I am to finish Dental school.
I am focused on continuing my studies and finishing school, but given the situation I find it hard to concentrate at times because of all the stress. I really like this girl and don't want to give up on her because of my father,, I have done that before, and it seems that no one is good enough for him. I also don't want my parents to think that I don't care about what they feel and think about them... I have a deep respect for both of them and care verry much about them, and fully realize how much they supported me my entire life. But the kind of pressure my father puts on me, and the fact that it's almost impossible to please him at times is too much, and him constantly pointing out how many sacrifices he has and makes for me is of no help, espacially because it seems that I should take full notice of his sacrifices without him considering mine at all, things like a battered childhood and teenagehood due too the fact that I pretty much was a house rat, and rarely got out to spend time with friends, because he considered most of them losers. I also fear that after I pass my exams in September, the issue will stop being that "I should stop dating her because she is interfering with my school" and will switch to "I should stop dating her because she is too old for me, and other types of nonesense".
How can I explain to him that I am not a child anymore, that he needs to let me make my own decisions, and let me learn from my own mistakes. I need him to back down, and understand that if threatens me into what he wants, threats of expulsion from the family, losing his support, whatever emotional support he thinks he gives, and financial support, he will only achieve in driving me away.
Thank you for taking the time to read this, sorry for the misspeling, I didn't Google every word to make sure it's correct. And please treat this seriously, it felt good to let it all out, but I would greatly apreciate some advice.