I'm just scared all the time.

[MrBond]

Why only 2-3 days? Maybe you can start adding a day or two and gradually make yourself more prominent. Most importantly, be there for the kids only. Don't have the attitude of "look I'm helping out! Aren't I a great father/husband".

When you do talk to her, look deeply into her eyes as if she's the most important person in the world. Like you're really paying attention to what she's saying. Not because you want her back but because you are genuinely interested.