Newton third law - contradiction?

Imagine two particles in space particle A and B. Both have same mass. A is accelerating towards B. B is at rest. Force exerted by A on B would be its mass times its acceleration. Its acceleration and mass is non-zero so Force must be non-zero too. Force exerted by B on A would be 0 since its acceleration is zero due to no change in velocity.

It violates the Newton third law. Both forces must be equal and opposite.

I know there is something with my reading but I am not able to figure it out