XP: If you have a few minutes- this is super duper long & I need advice

Backstory (as brief as I can make it): I was born in NJ. My parents were divorced when I was 1. They had me at 18. I would see my dad on the weekends semi-regularly until I was 12 and then my mom moved us to FL with her new husband. Within 9 months, I lost all contact from my dad. When I was 18, I found him on-line. He flew me to NJ to see him and said everything would be different and we would keep in touch, etc. I got back to FL, called him, sent a letter, no response. No contact from him again until I was 26. His new fiance found me on myspace and sent me a message. That was about 5 1/2 years ago now and we are still in touch. On facebook semi-regularly, call now and then, and see him about 1x a year. He and his wife visited LO and I three weeks ago for 2 days. He is still in NJ and I am in KY now.

Issue: My dad posted this on facebook the other day in response to a friend saying they wish they could retire but won't be able to until they die "Haha it seems like that's what we born to do right. Work our ass off to support our families and try to give everything we can to our kids even if we can afford it or not ( its not like they even appreciate either) until it puts us in the ground without so much as a TKS DAD."

This pissed me off. He has only been in my life a few years and when he sends me gifts for holidays,etc. I always say thank you. He and his wife took LO and I shopping while they were here and I gave them hugs and said Thank You. I am his only child. His wife does have a daughter, so I was hoping he was talking about her, but I (maybe I shouldn't have but I did) posted this response: "Do you have other kids? I know you aren't talking about me because I ALWAYS say Thank You!"

He sends a message to my inbox saying "Yeah ok Shawnee just like you said I love you too dad back to me after I said it to you when we were leaving KY the night before. Listen if you have no genuine feelings for me just say so I'm a big boy and can handle it."

I could be wrong, but I feel like this is the response of an immature 16-yr-old boy.

And I am pissed off again and not sure what my response to this should be. When we said goodbye, we were in the mall parking lot and I was with DH and DS. I don't recall what happened since I didn't have an issue with it but my guess is that either he didn't hear me say it- I tend to speak softly (and I have been saying it back to him when he says it) or I was busy getting DS in the car and didn't hear him say it, so I didn't reply. I was also annoyed because they were only in town two days and they stayed at their hotel until 3:30 that day and then said they were going back to the hotel to rest at 6:15pm for their departure the next day- spending a whole two hours and 15 minutes with us out of the day when we only see them 1x a year.

I have a lot of options of which I could reply and need your help. I don't want to fight with him (I am afraid he will disappear again) but this is not acceptable behavior either. I will number the information so you can tell me which things you think I should include in my reply:

1. I love him because he is my dad, but he has barely been in my life. I remember snippets here and there of hanging out with him before I was 12, but I don't remember a lot from my childhood and I only see him a couple days 1x a year, so it's not like we have time to build a strong bond. Realistically he is little more than an acquaintance to me.

2. I feel like he could be out of my life at any moment still and also wonder if he is only in my life now because of his wife (I hear from her more than him, she was the one who initially contacted me, and he never kept contact before her- he was out of my life by his choice- the only excuse he has ever given me is he was "young and dumb" and also blamed my mom- that's fine for his excuse from 12-17 but not from 18-26- I wasn't even living at home anymore).

 3. I am not super emotional. I am not the type to ever get super excited, jump up and down and be like "OMG- thank you!!!". I will say thank you and I mean it, that is all. I was abandoned by him, physically/emotionally abused by my step-dad, and raised by my emotionally unavailable functional alcoholic mother, so I have my own issues and trouble expressing myself.

4. Now that I have my own child, I don't understand how he could just drop out of my life like that? I could never do that to my son. Ever. 

I might add more later, but it's been a while since I first read it and my initial reaction, so I forget what else I thought at that moment. I don't know if I want to "beat a dead horse" about him being gone. He won't explain further and it's not something we can change now.