Feeling guilty comes under the five hindrances. You are supposed to do Dhammanupassana(mindfulness of phenomena) to overcome that.
Technically you did not lie to her as the word 'love' can take many different meanings including lust. But if you promised to care for her and make her your sole partner in exchange for intimacy, you can either keep that promise or apologize to her and determine never to trick people again.
Either way, if you expect considerable progress in Vipassana practice, you have to be celibate first. So you have to stop all sexual activities at least during those days/weeks/months you dedicate for meditation.