That must be very difficult Meow and confusing. Why contact you at all if you're going to be ignored when you respond?
We get nothing, and haven't for getting on for 10 years now and for me, that's preferable to your experience. Two years ago after almost 8 years of estrangement, our ES emailed me 2 days after my mum died. For me, that was an intrusion into my life that I felt he had no right to make, especially at such an upsetting time.
I responded because I didn't want to leave him hanging and I realised how hard it must have been for him to make contact. In your position I would give serious consideration to not responding in the future, but I understand that you would worry that by doing so, you may be preventing a possible reconciliation.
It's cruel to keep doing this to you and may be better for your well being if they stopped .