Estranged, what to put on card.

[Ermmmmname]

Small background, estranged from Father when I was 17/18. Seems to have worked out well for everyone that way.
Recently got to amiable ish status. Exchanging birthday/Christmas cards. His birthday is not too far off.
I’m not really sure what to write on the to section Dad or his name.
I don’t really call him Dad to anyone else because he’s not really done that in years. So it would feel weird to write it for me. But I think he also thinks everything is sorted an swept under the rug so might take offensive to me writing his actual name (he has been easily offended by a few ways of me keeping my distance before). He even put love on my birthday card but I’m definitely not up for putting that on his.
Just wanted an outside opinion on what to write?

Just miss off the "Dear Dad" bit altogether. Just put "Hope you have a good birthday, your name".

Just leave the top bit blank, it's not totally unusual so it won't look odd.

How did he sign off your card, was it ‘Love Dad’ or ‘Love Trevor’ (or whatever his name is)? Would you feel comfortable taking his lead?

Why send a card when he hasn't been in your life for such a long time?
I wouldn't bother. He's not acted as a father to you for many years. He won't change.

I like the suggestion of leaving the top off but DH just added what would I put on the envelope.
He signed mine off love Dad. Which felt weird and I wouldn’t really be comfortable following his lead on that.

I think the fact that he has been easily offended is actually a reason to be a bit more forceful with your boundaries. If he is willing to risk the relationship by sulking because you don’t call him dad then the relationship might not be worth it.

For the envelope put Mr Initial Surname, I do that if I address an envelope to any of my relatives. I'm assuming you're posting the card rather than hand delivering though.

Can you leave his name off the card and post it to him, so it would look less strange having Mr. F Bloggs?

Or, it might be time to let him know that, for you, things are not just fine and dandy and you don’t feel comfortable calling him dad.

I was going to give it to my brother to give to him but I might use a stamp to avoid using other names on the front, feels very British
I’ve been quite clear with how things are my end, he has appearances he would like to keep up and is always overstepping them his end. I’ve started to relish a bit in the awkwardness he creates though, not much else I can do!