Past simple tense is formed by adding -ed (in some cases, -d or -ied) to the base form of the verb. The past simple tense of the verb "to splurge" is going to be "splurged."
Past progressive form, on the other hand, consists of verb to be and -ING verb form - "was splurging."
Past perfect form would be "had splurged", while past perfect progressive would be "had been splurging."
