I'm not entirely clear what you mean by 'programmed' in this context. Did these tracks involve the playing of any real instruments, or were they generated entirely by software like Cubase? Assuming this was the latter and that you alone were responsible for manipulating the process, then you would be the sole owner of any copyright.
However, you used the word 'mainly' which implies there may have been some input from your former partner, and this may well have been sufficient that the copyright is now jointly owned by you both. The courts have looked at this sort of situation a number of times and generally take the view that where a song has been developed through rehearsal or improvisation all or the majority of the band members can be said to be the joint copyright owners in the work because it is impossible to separate out each person's individual contribution. The classic case involved the organ intro to the Procol Harum hit A Whiter Shade of Pale
. Incidentally that site - Music Law Updates - contains a wealth of useful information for musicians generally.
The amount of input doesn't need to be half each, just that the finished track would not have been the same but for the contribution of the minor contributor. The contribution doesn't need to be through playing an instrument and could have involved him making a suggestion to include various features which you then caused to happen via the software.
If these tracks are best described as works of joint authorship, then in theory neither of you can use them independently without the other's permission, so you would have a Mexican stand-off where either you both benefit from their use or neither of you do.
Only if you are certain that you alone composed or created these tracks do you have any right to stop the other guy from using them.
This kind of situation is all too familiar unfortunately, where creative people get stuck into doing what they enjoy and it is not until things turn sour that they consider the legal aspects. Since I doubt that these tracks have any significant monetary value at this stage, I think it would be a shame if any dispute over the ownership of the rights should overshadow the future creativity of you both.