How to get him to make up his mind?

This one is a little complicated - for the last almost 20 years I've been sleeping with this man. Both of us didn't have feelings for each other until the last few years. We are both in other relationships with kids but neither of us are happy. Given that feelings are now involved things have become incredibly more complicated. He said it might be a good idea that we stop doing this and try to move on- but ultimately we both agreed to stay.

The next time I saw him I asked him out right - do you really not want me in your life and he said 50/50 and he said its due to his guilt (feeling bad for cheating) and that its not my fault. I also asked him if when I message him if its bad he said 50/50 sometimes he's happy to hear from me sometimes he needs to not hear from him.

He has been miserable in his relationship for many years and has said over and over he's only there for the kids and that I make him feel like he deserves better. When I try having deeper conversations about this though he gets very aggressive and won't give me a clear answer about what's happening here or its direction - just that he cares about me. How do I get him to make up his mind and land on one side or the other of the 50%

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I message him if its bad he said 50/50 sometimes he's happy to hear from me sometimes he needs to not hear from me****
How to get him to make up his mind?
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