Here is someone holding back tears and trying not to let anyone see. The speaker feels close to crying, so they put on a mask to hide their face and keep their feelings private. The pain is real ("It hurts so much"), but instead of letting it out, they choose to "eat" their feelings, swallowing them down and carrying them until the next day. It's a vivid way of saying that emotion gets pushed inward rather than shared.
The two questions near the end show how fragile this control is. The speaker wonders whether they can avoid giving themselves away, and whether they can avoid "exploding." Those words suggest feelings building up under pressure. The final line, "I'll try not to," is quiet and uncertain. It isn't a confident promise, just a determined effort. The mood is tense and lonely, with a sense of someone struggling to hold themselves together. The title, "Crybaby," may hint at the shame the speaker feels about crying, as if showing sadness were something to be embarrassed about.