Yeah, HP--you've been though an awful lot these last few weeks.
Just read back through your threads...what a powerful change. You're in a new chapter of your life and it is going to be emotional for you.
You've had to hold it together for a long time, you should let it out. I think it's fine for your son to see this. What a great opportunity to show him that tears don't mean you're not a man, or that you're out of control.
Tears can mean you're sad, even while you're being brave, and that's what the two of you are doing, right?
You can tell your boy that crying means you have stuff inside that needs to come out, because if you hold it in all the time, it hurts you. Letting it out with someone you trust can help you feel better.
And maybe encourage him to talk about HIS feelings, he's got to be experiencing a lot of conflicting emotions right now--since you have learned some validation skills, you can let him express his sadness and concern about the future in the safety of your love for him.