The past tense of lose control of the situation is lost control of the situation.
The third-person singular simple present indicative form of lose control of the situation is loses control of the situation.
The present participle of lose control of the situation is losing control of the situation.
The past participle of lose control of the situation is lost control of the situation.
Win Amazon gift cards by writing simple stories at Fictish, a new story writing game backed by WordHippo.