Most likely you won't be calling it quits. You'll probably have a sleepless night tonight wishing you had just taken the points like you had probably considered but instead decided to take the "safe bet."
Everyone goes through such phases of gambling. You are basically an addict and a square/donkey anyway you look at it. You have to make a serious decision tonight. You either should stop gambling or learn how to become a better sports bettor. It's up to you what you want to do, but betting isn't the problem, it's your inability to be a successful gambler that is hurting you and will continue to hurt you in the future.
Listen to these 4 people at SBR: Ganch, Justin, Durito, and Don Juan.
Everything they say, write it down and committ it to memory. Just about everyone else at SBR is useless but that does not mean they are irrelevant. In fact, many of the most useless posters provide valuable lessons about what not to do. When you become real good, you can start critiquing them and identifying why they are losing gamblers. Once you are able to do that and do with that with a high level of confidence and accuracy, you'll know you've arrived.
You can take some solace in the fact that a lot of other posters on here lost big tonight with the same bet you did (or tied USC to every imaginable parlay they did this weekend) but again, most people lose so it is to be expected.
Good luck B2M.....