It's important to prioritize your comfort and boundaries in any relationship, online or otherwise. If you have already communicated your discomfort with his behavior and decided to end things, it's important to stick to your decision.

Here are a few steps you can take to handle this situation:

1. Clearly communicate your boundaries: Send a final message to him explaining that his sending explicit pictures made you uncomfortable and that you have chosen to end the relationship as a result. Be firm and assertive in your message, making it clear that you are no longer interested in pursuing any kind of relationship with him.

2. Block and delete: After expressing your decision, it's best to block his number and remove any connections you have with him on dating apps or social media platforms. This will prevent any further contact.

3. Stay strong: It's possible that he may try to reach out again, but it's crucial for you to stick to your decision and not be swayed by his attempts to reconnect. Remember, you deserve to be with someone who respects your boundaries and makes you feel comfortable.

4. Reflect on the experience: Take some time to reflect on this situation and what you have learned from it. Consider what red flags you may have missed initially and how you can better protect your boundaries in the future when engaging with potential partners online.

5. Seek support if needed: If you find yourself struggling emotionally with this situation, don't hesitate to reach out to friends, family, or a therapist for support. Talking about your feelings with someone you trust can help you process the experience and move forward.

Remember, it's essential to surround yourself with people who respect and value your boundaries.