It's tough. It's also normal. Me(M35) and my ex girlfriend broke up after 9 years. The dreams, the thoughts, the memories, took about 5 years to slow down. Eventually you'll stop thinking about him and then even when you do, the emotional reaction you get is almost zero.....just a memory with no feeling attached to it, which in and of itself is also a sad notion. Have patience that time will really bring you additional clarity as well as the strength to focus on building your future. The past becomes less and less significant the further along you get in life. Just think of somethings you experienced in your high school years that at the moment felt monumental to your existence at the time and yet here you are today and the importance of that moment is gone, it has no bearing on your happiness or wellbeing at all. The same will happen with your ex. Patience. Hope my life experience and perspective helps a bit.