What would be the best thing to do to get back on track after relapsing?

Forgetting this(clear your mind, ocupy with other thinkings and preocupations) and continue living your normal life

 

Be careful. The Western perception of Tantric practices have been misperceived. Especially during this New Age breakout of popular theme on meditation. While it is true that it could enhance your sexual energy through practice, Tantric practices is very esoteric. Meaning that you need a spiritual master to guide you. And I highly doubt, given the nature of the Capitalistic Materialistic western society today, that any of the Tantric master could give you a free course -- let alone paid course. Because the Tantra itself meaning 'hidden', 'esoteric', 'secret'.

I would rather suggest to take a broader path and simplest -- yet powerful -- meditation; which is Theravadin Meditation.
That is divided to two categories. Samatha for Tranquility; and Vipassana for Insight.

While also Vipassana course have become popular these past decades. It needs a heavy emphasis on practice -- personally guided.

I would suggest Samatha, with the Object of Meditation of 'mindfulness of breathing', where you become mindful of your own breath. Good luck! Oh, and there are many YouTube videos that can explain to you the ways toward Anapanasati (mindfulness of breathing) meditation.

 

Get back up with no shame or guilt.

 

Don't worry about it since you didn't PMO just pick yourself up and continue

 

I don't know much about meditation. But since you mentioned you wanted ways to use that energy, I would like to recommend weights and/or cardio. Even going for a bike ride or walk can help.

Whenever I get off track, a bit of exercise, healthy food, and change of scenery (read: get outside away from screens) does wonders for me.

Regarding guilt: Take it easy on yourself man. While you can one day live without PMO entirely, any flip ups along the way are lessons to learn from rather than reasons to give up or feel bad.