How to get over my ex?

Me and my ex broke up around a year ago. After the break up we never spoke again.. I thought I was doing fine all this time as when we broke up I went on a holiday and had some fun but recently he got a close mate of his to contact me on Facebook. He didn’t realise I would know it’s his mate as I asked someone else and figured it was. So basically got him to msg me to see what I would say back as my ex was very jealous of other males. After this happened which was 2 weeks ago I can’t stop thinking about him and wishing he would show up and come back to me. It’s starting to kill me. How do I get back on track? I don’t want suggestions to see orher men as I haven’t seen anyone in the whole year and wouldn’t want to just to get over him