How old is your son OP?
My daughter was 18 when she told us, so legally an adult. We have followed her wishes and use her new chosen name, she has had all her ID papers changed (name and sex marker).
Whilst we respect that it's her life and her choice, we have been very clear that she will never be able to "change sex", not even taking cross sex hormones will change her sex. She understands this position, but is apparently happier "presenting as male" (whatever the fuck that means... gender ideology forces gender stereotypes more strongly than plain ol' misogyny).
It's not an impasse exactly, but an understanding that we love each other as members of a family and that opinions are allowed to differ.
So now I have a trans son. I cannot, or will not, say I have a son because I need to draw a line (for myself, for my own sanity). I do feel compelled into living a lie by using the wrong sex pronouns for my child, but it's a compromise I'm willing to make currently because I love my child.
OP if you have a close relationship with your child up till now, and you want to maintain that, it will be up to you to decide how you can adjust and accommodate to this new phase in your relationship together.
What I tolerate and accept may be very different from what you're able to. I remind myself that in 5, 10 or 20 years' time, I want to be enjoying a meal or some kind of happy time with my children so I do what I can now to ensure my child knows I love her, despite our differences of opinion and acceptance of reality.
Good luck, and do look into joining Bayswater Support Group if you want support from other parents in the same situation.