My professor is being a dick!!! (Sorry It's a bit long)

I have really kept this to myself for the longest time because I feel like I put myself in this situation and I really do not want anyone to judge me.I am currently a freshman at Georgetown university, unfortunately, I have no friends at the school I don't know if there is something wrong with me or if the people here are just not friendly.I am also an out of the closet gay.A few months ago in my first semester, I went to a gay bar, I had no idea what kind of gay bar it was because I just googled the place and went to the nearest one close to me. As it turns out it was filled with older men and I was basically seen as fresh meat to them, I was being hit on anyhow and I know some people like that stuff but I have some serious anxiety issues and I did not like it one bit so I decided to end it. While I was leaving the bar, Someone came to talk to me on the street and I am not into older men or anything but he seemed very nice and he looked good so we hit it off. I gave him my number and we had sex that night, I am not a whore or anything but he was very persistent, A few days later I found out that he was my philosophy professor, I was very scared but I figured that we were in a huge lecture hall so he would not see me, unfortunately my phone decided to ring out loud and everyone noticed including the professor he didn't even seem shocked to see me, he just smiled and continued teaching.When I got back to my dorm he called me and asked if he could see me I wanted to say no but he convinced me to come and I met him for dinner, I met him for dinner and after that we went back to his house and while I was there I saw pictures of people that were obviously his family,he had a wife and 2 sons who looked like they would be my age mate, I felt bad because I never thought that I would find myself in such a situation, and being from a broken home myself I know the kind of drama and pain being unfaithful can bring to a family,but he was very convincing and he told me it doesn't matter and it was just a fling.I don't want to seem like a fool or anything but he actually was convincing and he did know the right thing to say all the time. We had sex that night and several times after that and we eventually began to have an emotional relationship which was put forward by him and I must admit I did like him too so I agreed to be in a relationship with him. It was nice he used to buy me stuff and give me cash and tell me how much he loved me and he used to help me with the course and give me 1 or 2 extra marks on my papers and midterms, which might seem small but in college that is really a big deal. The relationship continued for quite some time, but a few weeks ago when I was leaving his house I saw one of his sons outside the house and I had to lie that I was his TA and I had to submit some stuff so he didn't get too suspicious. He then continued to make conversation with me and I found out that we were both 18 and I found out how much he admires his father and I instantly felt sick to my stomach. I ended the relationship the next day he didn't take it lightly at all he was really angry and I was very scared. Since then I have been avoiding him in classes and I deleted his number from my phone. Now the problem is that since I ended our thing I have submitted 7 papers and in 5 of those papers I have gotten D's and I got straight up F's in the other two. And I cannot say I didn't expect this to happen but I had no idea he would fail me this bad I am not a bad student, I know I am an above average student may be an A- or a B+ kind of student so you see my confusion as to the reasons I am getting D's and F's. Aside from that I have been constantly getting emails and text messages from him saying that he wants me back and some of them have been quite scary, I don't know what to do I have no friends to talk to about this and mid-terms are coming up and I don't think I would be able to handle getting an F in my midterm, Please can anyone tell me what to do I know this is my fault but please this is really serious, I care alot about my education and I dont want a tiny mistake to mess up my life.