When is the best time to severely cut back cotoneaster horizontalis?

I thought about pruning it last spring, after it had flowered, but I didn't
want to lose the berries. But if I cut it back now then I'll lose the
berries now as well as next year's flowers anyway, right?

Will I have to resign myself to losing a year's worth of flowers and berries
no matter what I do?

And, it will grow back after a SEVERE pruning, right?

Thanks.