I'm so sorry to hear about your dilemma.
Firstly, disregard the dad's opinion. He has no right to tell you what to do. He is an immature arsehole. Abortion to him would be nothing more than squashing a mosquito. By "ruin his life" he's thinking of child support. But he doesn't have to be forever bound to this child (emotionally) but you almost certainly will.
I don't know your family but if they're at all reasonable, you really need their help. Tell trustworthy relatives and friends. You can't be on your own when about to make a huge decision like this, and it will eat away at you if you do get rid and never tell them..
You must do your research, whatever you want to do. Look up pregnancy advisory services and charities. Get support from unbiased organisations - not religious, or anyone who earns money from providing abortions.
How many weeks pregnant are you? Look up what the baby is like at that stage of development and the relevant abortion procedure, and judge whether you would feel comfortable with that. The foetus is not killed prior to being removed if it's younger than 21 weeks, and some abortion procedures sound a very unpleasant way to die. In fact, it would be informative to know all the stages of development of the foetus.
Also see what financial help you could get from the government, and free nursery places etc should you keep it.
It's true that it's possible to go through school with a child, but it would be very hard, you would need to live nearby and your family would need to look after the child for most of the day. Many families find it suits them for the young mother to have the role of an involved big sister, and for the baby to be taken care of by older relatives.
You will probably pine for the baby while you are away from it, and at the start of the school year you will have just recently gone through childbirth and would need to be recovering. Looking after a baby is very hard and they need constant attention, day and night, and this pretty much continues until they're old enough for school or nursery. You would lose your freedom for years and you are only young. Also, sadly, men are less interested in being in relationships with mums. They don't want the "baggage". It shouldn't be that way, but sadly men can be immature.
If I were you I'd end the pregnancy, but only enough if it was early enough for a medical abortion.