Layer seperation

That part should be ok, but long thin things are susceptible to this kind of trouble. 2 walls / 25% should be well in.

First step would be more squish - increased wall thickness relative to nozzle diameter and layer height. Increase your wall thickness in slic3r to at least 0.50mm (1.2-1.5x nozzle diameter, which is usually 0.40mm on newer SD's), and don't use a layer height over 0.30mm. You may want to do a single-wall calibration to check you're getting what you set, usually if you're dialed in with one wall thickness, changing this setting works pretty well.

Make sure your SD is enclosed, and you let it warm up well before starting the print - higher ambient temps help reduce the warping forces, which can be surprisingly annoying with ABS!

Also maybe try increasing extrusion temperature by 5-10 C, this often promotes better adhesion (but be cautious, as going too high will cause re-melt, squidgy corners, increases the risk of clogs, and may even increase the problem as the dT is larger from application to cool...).