Need to change facebook password but dont know my gmail password

Hello, long story short, I created my Facebook and gmail a few years ago. My parents have since gotten mad at me and changed my Facebook and gmail password. They eventually told me my Facebook password so I have full access to that but they forgot my gmail password. I have recently broken up with a boyfriend who had my facebook password and I need to change my password asap. I tried going through that long process to get it back on gmail but all of my contact information has changed since I got it and it said none of my given information matches (go figure) so I don't know of any other way to gain access to it and change my password. Is there another way or do I just need to delete my Facebook? Thanks in advance!