I'm 21, and I've started my path for my current company when I was 16 in a school internship. Then for all next years every internship or every holidays I was working for them as a software developer. When I reached 18 I started to work part-time, morning school and evening work. Then after the end of the high school, I've started to work full-time, so under contract I have been here for more than three years and I'm known in the company for more than six years.
After all those years my pay never raised. There is zero organization in the company and almost all projects were under me as I was the only developer to know new technologies and that caused a high level of stress for me.
So I've started to look for other work...
I've done lot of interviews with different companies and when I said to my boss that I was going to change he told me that my pay would be changed in X (actually it wasn't even a significant raise), so we started to discuss about it as X was too low for the job I was actually doing. We ended up with something that would be "okay" for me and he even told me that I would become the manager of the software office and he was going to say it to the current manager and other developers, but in one month he still didn't said anything to others about it, (we're in 5). I've accepted it.
The issue is that after some days I had a positive feedback from an interview from another company, much bigger than the actually one, and flexible hours, lot of benefits. The pay is lower, but I would learn a lot and I would focus only on something specific instead of doing all of the work as I was doing for all those years.
So I accepted it. The issue is that now I have to tell it to my boss who has seen me growing up and helped me a lot in my personal life. He was like almost a "father" for me with obviously all the cons about the "life" in the company.
How should I tell it to him?
He is an old man, and he was saying lot of emotional stuff every time I was talking about other companies like "remember all stuff I've made for you" and so on...