Albert Barnes Commentary Philippians 4:14

"Howbeit ye did well that ye had fellowship with my affliction." — Philippians 4:14 (ASV)

Notwithstanding you have well done. Though he had learned the grace of contentment, and though he knew that Christ could enable him to do all things, it was well for them to show sympathy for his sufferings, for it demonstrated a proper regard for a benefactor and an apostle.

You did communicate. You shared in my affliction. That is, you sympathized with me and assisted me in bearing it. The relief which they had sent not only supplied his needs, but it sustained him by the certainty that he was not forgotten.

The phrase with my affliction means that they "Have jointly contributed to relieve" it.